glass product training - sanam glass

Sanam Glass – Sales and Technical Training June 2013

Sanam Glass Sales and Technical Training


•  General understanding of glass production, processing and fabrication. •  Information on value-added glass products such as tinted glass, coated

glass, laminated glass, etc. •  Basic understanding of glass fabrication processes and glass installation. •  Provide insight to glass and glass-industry terminology. •  Resource that you can keep for reference. •  General Coated Glass sales technics for Customer and Architect •  How Vision SLM can assist you – action and support.

Question are encouraged – any time during the presentation

Glass Product Training


I – The History of Glass


History of Glass Objectives

•  Provide a brief background on the history of glass manufacturing.

•  Give insight into the glass markets of the past.

•  Raise awareness of the historical importance of glass.


History of Glass Overview

•  Natural Glass •  Nature’s Raw Materials •  Earliest Man-Made Glass •  Glass Blowing •  Glass Development and Science •  Early Flat Glass Production •  Modern Flat Glass Production (Float Glass)


Glass Fundamentals - What is Glass?

•  Glass is derived from the late-Latin term “glaesum” used to refer to a lustrous and transparent material.

•  Has the combined properties of crystal solids and amorphous liquids but is distinct from each –  Mechanical rigidity of solids –  Random disordered molecular arrangement of

liquids

•  Formed by melting specific crystalline materials at high temperatures and cooling the melt before the atoms can order into a crystalline arrangement.


Glass Fundamentals - What is Glass?

•  Usually transparent or translucent. •  Tens of thousands of workable

glass compositions. –  Compositions determine

properties –  New formulations developed

every day •  Can be coated and tinted to alter

optics – aesthetics and solar performance.

•  Can be strengthened, bent, laminated and fabricated into a wide variety of applications across many industries.


History of Glass - Natural & Volcanic Glass

•  Obsidian –  Glass formed by volcanic action –  Shiny black, orange, red, or green –  Transparent or translucent splinters –  Chipped and flaked to make arrows,

spearheads, knives and razors –  Earliest obsidian tools from 75,000 BC

(Paleolithic Age)

•  Tektites –  Glass objects from meteor impacts –  Libyan Desert Glass

•  Sahara Desert impacts •  Yellow silica glass lumps created by meteors


History of Glass - Early Glass Raw Materials

•  Glass is an amorphous substance made primarily of silica fused with alkaline at a high temperature. –  Silica was obtained from:

•  Sand •  Quartz •  Flint

–  Alkali was generally: •  soda-ash (obtained from burning seaweed) •  potash (obtained from burning brushwood).

•  To these fundamental materials, other ingredients were added to obtain different effects. –  The addition of lead, for example, produced glass of a distinctive clarity

and brilliance –  Glass was also colored by the addition of naturally occurring sulfides

and metallic minerals


History of Glass - Man-Made Glass

•  5000 B.C. – Glass ‘discovered’ in Syria by sea merchants –  Readily available raw materials + fire

•  3500 B.C. – Man-made glass techniques developed in Egypt and Mesopotamia –  Beads –  Glazes

•  1500 B.C. – Glassmaking developed in Greece, China and Central Europe –  Development of hollow glass techniques (molds) in Egypt…led to

bottles, flasks and containers •  650 B.C. – First glass-making manual •  27 B.C. to 14 A.D. – Glass-blowing techniques developed •  100 A.D. – Discovery of casting flat clear glass by Romans

–  First cast glass windows


History of Glass - Glass Blowing and Casting

•  Glass blowing was developed by Syrian craftsmen in 27 A.D.

•  It was later adopted by the Romans circa 100 A.D. •  For centuries glass was melted in a pot furnace. •  The raw materials were charged, melted, conditioned

and then worked by hand, or cast. •  Working the glass was done by a team of highly

skilled workers and glass blowers (gaffers). •  Today’s hand-worked glass is nearly identical to the

earliest methods on record. •  Most hand blown-glass items today are decorative.


History of Glass Glass Development & Science •  Need for high quality glass was central to a

variety of scientific revolutions: –  Glass windows (up to the 1400’s)

•  Replaced dark wooden shutters/oiled paper in Europe

•  Development of superior mirrors in the 1400's heightened awareness of cleanliness and hygiene

–  Optical Glass (1500's) •  Microscopes (Huygens) revolutionized biology •  Telescopes (Galileo) revolutionized

astronomy –  Thermometer Glasses (1800's)

•  Accurate/reproducible measurement of temperature responsible for experimental basis of thermodynamics

–  Laboratory Glass (1800's) •  Chemical revolution (Michael Faraday)


History of Glass -Early Flat Glass Production From Craft to Industry

•  In 1100-1200 A.D. – Germans and Venetians developed methods for blowing and spinning glass into flat sheets. –  Glass was hand blown into a globe (Crown

method) or cylinder (Cylinder method), pierced or cut, and spun or laid flat into a disc or sheet.

–  Glass was annealed, then cut down into smaller plates and glazed in place.

–  Stained-glass church windows were a primary market for flat glass.


History of Glass - Early Flat Glass Production From Craft to Industry

•  1700 A.D. – The flat glass cast process (plate pouring) was developed in France to make glass with superior optical properties. –  Mainly for mirrors and optics –  Glass poured on special table and then

rolled flat –  After cooling, glass was ground with

increasingly fine abrasives –  Low melting point metals applied as

coatings on one side of the glass provided high quality mirrors


History of Glass -Early Flat Glass Production The Improved Cylinder Method

•  In the early 20th century glass was: –  Drawn into cylinders up to 5 stories high

and allowed to cool –  Sectioned into tubes –  Diamond cut –  Reheated in a special kiln –  Annealed and flattened onto a piece of

polished glass, which preserved its surface

•  In 1871, William Pilkington invented a machine which took over the functions of supporting, swinging and rotating the glass cylinder, thereby enabling even larger sheets of glass to be made.


History of Glass -Early Flat Glass Production Industrial Development •  It took until the later stages of the Industrial

Revolution for automated glass production technology to be fully developed. –  1905-1914, Fourcault developed a method to

draw a continuous sheet of glass vertically with a consistent width.

–  1909, Bicheroux developed a process to pour molten glass through rollers.

–  1917, Colburn developed another method (Libbey-Owens) of drawing sheet glass and transferring it horizontally.

–  1928, Pittsburgh process was developed. •  Pittsburgh Plate Glass (PPG) improved

method until 1960s with quality equal to early float.

–  1959, Float Glass Process developed by Pilkington Bros.

LOF - Coburn

PPG- Pennvernon


Annealing Lehr Furnace

Molten Tin Bath

History of Glass - Early Flat Glass Production Modern Flat Glass Production

•  The modern “Float” process was invented by Sir Alistair Pilkington in the 1950’s and 1960’s.

–  Revolutionized industrial glass making like no other single process. •  Consists of a continuous process of “fire-finishing” the glass by

floating it on a bath of molten tin. –  The glass cools on the tin until it hardens.

•  Natural gravity and tension combine to make the top of the glass as smooth as the bottom.

–  No polishing required for a finished product. •  The process combines the brilliant finish of continuous sheet

glass with the superior optical properties of polished plate glass.


II – Glass Composition, Structure & Properties


Glass Composition Structure & Properties What is Glass? Early Definitions

•  Glass is an amorphous solid. •  Glass is a material, formed by cooling from the liquid state, which

shows no discontinuous changes at any temperature, but becomes rigid through a progressive increase in viscosity.

•  Glass is an inorganic product of fusion cooled to a rigid condition without crystallization. –  In reality, glasses need not be inorganic nor made by fusion from the

liquid state.

•  Vitreous is the term used to describe the glassy state.


Glass Composition Structure & Properties

Glass Composition

Glass Properties Glass Structure

Soda-Lime Pyrex Etc.

Like any material and especially for glass, the composition, structure

and properties are interrelated.

NBOs Free Vol.

Etc.

Viscosity Thermal

Expansion Surface Tension

Density Etc.

These three things, Composition, Structure and Properties allow a

scientist to measure and understand glass and the technologist to work with

and produce glass.


Glass Composition, Structure and Properties

•  The properties of glass are defined almost exclusively by its chemical composition and structure. –  Optical

•  Transparency •  Color

–  Thermal •  Viscosity •  Expansion

–  Mass transport •  E-conductivity •  Durability

–  Mechanical •  Hardness •  Strength

•  The unique glass structure allows for large variations in possible composition.


Glass Composition Structure & Properties Glass Structure

Glass Composition


NBOs Free Vol.

Etc.


Glass Composition Structure & Properties Structure of Liquids and Solids

•  Gases –  No Definite Volume, No Definite Shape

•  Liquids: –  Definite Volume, No Definite Shape

•  Atoms/molecules moving rapidly •  Bonds breaking and reforming •  Fluid behavior

•  Solids: –  Definite Volume, Definite Shape

•  Local positions of atoms are fixed •  Bonds are intact •  Rigid behavior •  Regular, wide-range order of atoms in crystal lattices

Solid Liquid


Quartz (SiO2) Crystalline Solid

Short and Long Range Order

Glass SiO2 Amorphous Solid

Short Range Order No Long Range Order

Oxygen Silicon

Glass Composition Structure & Properties Structure of Crystals vs. Glass

•  Difference between solid crystals and solid glass –  The positions of 'fixed' atoms are

different. –  In a crystal, atoms have ordered

positions, long-range order. –  In a glass, there is gradual

solidification, where 'frozen-in' aspects of the 'liquid-like' structure result in no particular long range order.


Glass Composition Structure & Properties Behavior of Molten Liquids


Glass Composition Structure & Properties How Glass Is Different?

Crystalline solids follow a well-defined path to solidification

Thermodynamically Stable

Lower Energy

Equilibrium Conditions

Non-Crystalline solid (glass)

Non-equilibrium path

Favored by Fast Cooling & High Viscosity

Slow atomic motion prevents long range order that constitutes crystalline solids


Glass Composition Structure & Properties Is Glass a 4th State of Matter?

No. •  Glass is metastable. Liquids and solids (and gases) are thermodynamically

stable. –  Any two of the three state variables Pressure, Volume, Temperature uniquely

defines the third. –  This is not the case for glass.

•  Its behavior is unique but not sufficient.


Glass Composition Structure & Properties Glass Composition

Glass Composition


Soda-Lime Pyrex Etc.


Glass Composition Structure & Properties Chemical Composition of Glass

•  Glass is made of a mixture of metal oxide components. –  Network Formers –  Fluxes –  Stabilizers

•  Low cost sources of these oxides are some of the most abundant minerals on earth. –  Sand –  Soda Ash/Wood ash –  Limestone

•  These materials are mixed together in certain proportions, then heated to high temperatures in a furnace and cooled in a controlled manner.


Glass Composition Structure & Properties Types of Glass - Soda-Lime Glass •  Commercial Glass (Soda-Lime Silicate Glass)

–  Soda-lime glass is what is made on Guardian float lines –  Most Common - 90% of all glass made is soda-lime

•  Common Composition –  ~70-75 wt% Silica (excellent glass former) –  ~12-18 wt% Soda Ash (Sodium Oxide) added as a flux –  ~5-11 wt% Limestone (Calcium Oxide) added because of the

poor durability of binary Na-silicates; (glass formation is difficult in the binary CaO-silicate system)

–  ~1-3 wt% Magnesia (Magnesium Oxide) –  ~1 wt% Al2O3 to suppress devitrification and improve durability

•  Basic composition set in the 1800’s –  Actual compositions depend on relative costs of raw materials.

•  Can vary by a couple of wt% without much variation in glass properties


Glass Composition Structure & Properties Typical Composition - Soda-Lime Glass

Aluminum Oxide0.7%

Magnesium Oxide3.6%

Sodium Oxide 13.8%

Calcium Oxide 8.6%

Silicon Dioxide 72.8%


Glass Composition Structure & Properties Types of Glass - Soda-Lime Glass

•  Melted at 2800°F (1500°C) –  Practical temperature for melting

•  Very clear and stable •  Easily tinted or colored

–  Elements like iron can create tints

•  Easy to obtain raw materials are relatively inexpensive and available


Glass Composition Structure & Properties Types of Glass - Soda-Lime Glass

•  Manipulating the composition of soda-lime glass alters properties: –  Higher SiO2, Al2O3 or CaO provide improved

weather resistance

•  Higher Na2O (Sodium oxide) makes it susceptible to corrosion –  Can also be a issue when coating glass

•  The art of industrial glass production is finding and maintaining the ideal composition while taking into account: –  Cost –  Processing requirements –  Application


Glass Composition Structure & Properties Glass Properties

Glass Composition


Viscosity Thermal

Expansion Surface Tension

Density Etc.


Glass Composition Structure & Properties Characteristics of Glass •  Glassy materials exhibit a transition range.

–  Volume/Temperature Diagram •  Viscosity behavior allows variety of forming methods

–  Numerous products are made of glass •  Glass has extremely high strength in compression.

–  ~106 psi –  Very brittle in tension

•  Glass is typically transparent, but can be easily colored or opacified by small changes in composition –  More liquid-like than solid behavior

•  Very good resistance to chemical corrosion •  Chemically inert and harmless to the environment •  Large range of possible compositions and properties


Glass Composition Structure & Properties Glass Properties Mechanical Properties

•  Strong –  High Inherent Tensile Strength

•  Weakened by surface imperfections •  Can be strengthened by (thermal or chemical) tempering •  Compositional changes within each type of glass have little effect on

tensile strength

–  Relatively Hard •  Resists scratches and abrasions.

–  Perfectly Elastic •  Gives under stress, up to a breaking point, but rebounds to it’s original

shape

–  Very Brittle •  Hard substance with limited tensile strength


Glass Composition Structure & Properties Glass vs. Steel Mechanical Properties

Property Annealed Glass Tempered Glass Steel

Density 156 lbs./ft.3

(2.5 g/cm3)

156 lbs./ft.3

(2.5 g/cm3) 490 lbs./ft.3

(7.8 g/cm3) Tensile Strength 30* – 100** N/mm2 50* – 150**

N/mm2

360 – 510 N/mm2

Compressive Strength

700 – 900 N/mm2

700 – 900 N/mm2

1440 – 2040 N/mm2

Modulus of Elasticity

7.3x104

N/mm2

7x104

N/mm2

2.1x105

N/mm2

Hardness (Knoop)

575 kg/mm2

+/- 30 575 kg/mm2

+/- 30 550 kg/mm2

+/- 30 *Tensile Strength of Glass for engineering purposes.

**Tensile Strength of Glass measured.


Glass Composition Structure & Properties Glass Properties Chemical Properties

•  Corrosion Resistant –  Affected by few chemicals –  Resists most industrial and food acids –  Affected by hydrofluoric and phosphoric

acid (etchants) •  Prolonged exposure to liquids or vapor,

such as water, causes the sodium/alkali ions to migrate to the surface of the glass –  Cloudiness or haze during high humidity

storage or if the glass gets wet and sits –  Attacked by concentrated sodium

hydroxide –  Placing a "barrier” coating, such as silicon

dioxide, on the glass will limit the amount of reaction

Untreated Treated


Glass Composition Structure & Properties Glass Properties Thermal & Electrical Properties

•  No defined melting point –  Softening temperature –  Between 1022°F/550°C - 1112°F/600°C

•  Shock Resistant –  Withstands intense cold and heat (ULE, or glass ceramics) –  Can withstand vast temperature changes

•  Low Thermal Expansion –  Volume changes very little with temperature

•  Thermal Insulator –  Resists the flow of heat rather than conducting it –  Absorbs heat better than metals

•  Glass is an electrical insulator as a solid. –  Does not conduct electricity


Glass Composition Structure & Properties Glass vs. Steel Thermal Properties

Property Annealed Glass Tempered Glass Steel

Coefficient of thermal expansion

at 68°F - 572°F (20°C-300°C)

9.0 x 10-6

K-1

9.0 x 10-6

K-1

1.2 x 10-5

K-1

Coefficient of thermal conductivity

1.0 W/mK

1.0 W/mK

50 W/mK

Resistance to temperature difference

40 K

100 K

N/A

Short Term Long Term

Max. Operating Temp.

550 °F 392 °F

392°F 392°F

N/A N/A


III – The Optical Properties of Glass


Optical Properties of Glass -History

•  Optical science parallels the history of optical glass development.

•  Ability to tailor the refractive index and the dispersion of glass for telescopes and microscopes led to advances in: –  Modern astronomy, Biology & Medical

sciences •  Each of these sciences depended on

the skills of the glassmakers. •  Modern glass science began with the

collaboration (in the late 1800’s) of: –  Ernst Abbe: physicist, specialized in

optical design –  Otto Schott: glassmaker –  Carl Zeiss: optician/instrument maker


Optical Properties of Glass Fiat Lux “Let There Be Light!”

•  Light is another name for the Electromagnetic Energy Spectrum. –  Radio and Microwave: basis for communications,

microwave heating –  Infrared : Heat –  Visible : Basis of human sight –  Ultraviolet : Less ionizing, but damaging (fading,

sunburns etc.) –  X-rays and Gamma Rays: High energy, ionizing

radiation, very damaging


Optical Properties of Glass Electromagnetic Spectrum

Most Important Region for Glass

Products


Optical Properties of Glass Electromagnetic Radiation Waves/Particles

•  EM waves are traveling & oscillating, electric and magnetic fields which are emitted by vibrating charges.

•  The electric and magnetic fields carry energy.


Optical Properties of Glass Electromagnetic Radiation Waves/Particles

•  All electromagnetic waves travel at the speed of light in vacuum (i.e. the wave speed = the speed of light).

•  Light can also behave like a particle (photon). –  The weight of an electron with no charge –  As witnessed by a shadow…the light

travels in a straight line from the sun and is blocked by your body


Optical Properties of Glass Types of Light Ultraviolet (UV)

•  100nm-400nm wavelength •  Arbitrarily broken down into three bands,

according to its anecdotal effects –  UV-C (100-280nm) –  UV-B (280-315nm) –  UV-A (315-400nm)

wavelength


Optical Properties of Glass Types of Light Ultraviolet (UV-C)

•  UV-C (100-280nm) –  Completely absorbed in air –  UV-C photons collide with oxygen and

form ozone –  Rarely observed in nature, since it is

absorbed so quickly –  Germicidal UV-C lamps used to purify air

and water –  Dangerous to life forms

wavelength


Optical Properties of Glass Types of Light Ultraviolet (UV-B)

•  UV-B (280-315nm) –  Most destructive form of UV light. –  Enough energy to damage biological tissues, yet

not quite enough to be completely absorbed by the atmosphere

–  Known to cause skin cancer –  Most extraterrestrial UV-B light is blocked by the

atmosphere –  Changes in the ozone layer could dramatically

increase UV-B reaching earth

wavelength


Optical Properties of Glass Types of Light Ultraviolet (UV-A)

•  UV-A (315-400nm) –  Least harmful and most common –  Lowest energy (close to visible light) –  Often called black light –  Used for its ability to cause fluorescent

materials to emit visible light - thus appearing to glow in the dark

–  Phototherapy and tanning booths use UV-A lamps

wavelength


Optical Properties of Glass Types of Light Visible Light

•  Visible light waves are the only electromagnetic waves we can see. –  Witnessed by the colors of the rainbow

•  Each color has a different wavelength –  Red has the longest wavelength and lowest

energy. –  Violet has the shortest wavelength and highest

energy. –  When all the waves are seen together, they make

white light.


Optical Properties of Glass Types of Light Visible Light

•  When white light shines through a prism or through water vapor, the white light is broken apart into the colors of the visible light spectrum.

•  Cones in our eyes are natural receivers (detectors) for these tiny visible light waves.

•  The Sun is a natural source for visible light waves and our eyes see the reflection of this sunlight off the objects around us.

•  The color of an object that we see is the color of light reflected. All other colors are absorbed.


Optical Properties of Glass Types of Light Infrared (IR)

•  IR light lies between the visible and microwave portions of the electromagnetic spectrum. –  It contains the least amount of energy per photon

of any other band. –  “Far” infrared waves are thermal and can be

detected as heat. –  Shorter, near infrared waves are not “heat” and

are used by in applications like TV remote controls.


Optical Properties of Glass Types of Light Infrared (IR) •  Infrared is unique in that it exhibits primarily wave properties.

This can make it much more difficult to manipulate than ultraviolet and visible light:

–  Infrared is more difficult to focus with lenses –  Refracts less –  Diffracts more –  Difficult to diffuse

•  Most radiometric IR measurements are made without lenses, filters, or diffusers, relying on just the bare detector to measure incident irradiance.

•  Humans, at normal body temperature, radiate most strongly in the infrared a wavelength of about 10 microns.

Hum

an Heat


Optical Properties of Glass Breakout of Solar Radiation Energy

Visible(380-780nm)

49%

Near IR(780-2500

nm)49%

UV(300-380nm)

2%


Optical Properties of Glass Sources of Visible Light

•  Natural –  Sunlight –  Moonlight –  Stars/Comets –  Aurora Borealis –  Lightening –  Natural Fires –  Volcanoes –  Bioluminescence


Optical Properties of Glass Sources of Visible Light

•  Artificial –  Incandescent Light Sources (i.e. Light

Bulbs) •  Radiate light by heating something to

glow –  Fluorescent

•  Electric discharge through a gas •  Mercury or phosphorus vapor

–  LASERS and LED’s •  LASER - Continuous beam of a single

wavelength •  LED – Monochromatic emission from

a semi-conductor


Optical Properties of Glass Sunlight •  The Sun radiates energy from gamma to radio waves •  99% of sun's radiation falls between 0.2 - 5.6µm •  80% - 0.4 - 1.5µm (visible and reflected infrared) •  Maximum radiation occurs 0.48 µm (visible blue) •  16% of shortwave solar radiation absorbed by atmospheric gases •  2% by clouds


Optical Properties of Glass Sunlight and the Atmosphere

•  Atmospheric gases - selective absorbers (filters) w/ reference to wavelength –  Gamma and X-ray - completely absorbed in the upper atmosphere by Oxygen and Nitrogen –  <0.2 µm (Ultraviolet) - absorbed by molecules of oxygen (O and O2 combined form ozone); –  0.2-0.3 µm ozone absorbs UV w/ wavelengths in stratosphere –  0.9-2.7 µm (Reflected IR) - water vapor and carbon dioxide absorb in narrow bands –  5-8 µm and 20 µm-1,000 µm (Thermal IR) - strong absorption by water vapor between –  9-10 µm - Ozone –  14-20 µm – Carbon Dioxide –  Microwave region - Three relatively narrow absorption bands occur between 0.1 - 0.6cm

(oxygen and water vapor) –  Beyond 0.6cm , atmospheric gases generally do not impede passage of microwave radiation. –  Absorbed radiation heats the lower atmosphere


Optical Properties of Glass - Defined

•  Bulk Properties –  transparency –  refractive index –  optical dispersion

•  Wavelength-dependent optical properties –  UV –  Color –  IR

•  Non-traditional, 'induced' optical effects –  Photosensitivity –  Photochromism –  Faraday rotation, etc.

•  All of these depend on how glass responds to exposure to light.


Optical Properties of Glass What Happens to Sunlight (or any Light) Shining Through Glass?

•  Reflection

–  The fate of the beam will depend on the nature of the glass material and its surface.

–  At the first interface some of the light may be reflected. (~4% for clear glass).

–  Smooth surfaces will reflect in a mirror-like manner. –  Rough surfaces will reflect the light in a diffuse manner

(many directions).

Diffuse Reflection

Specular Reflection



•  Transmission –  If most of the light is transmitted through the glass

without scattering or absorption, the glass is transparent.

–  If there is selective absorption of particular wavelengths but not others, there will be transparency along with color.

–  Any transmitted light will be deviated from its original path (refracted).


Optical Properties of Glass What Happens to Sunlight (or any Light) Shining Through Glass? •  Scattering

–  Some light may encounter obstructions in its path and be deflected and re-emitted in various directions or scattered.

•  If the obstructing elements are large compared to the wavelengths of the beam, all wavelengths are affected and any image of the light source is degraded (as in foggy weather).

•  If smaller elements relative to the light wavelengths are encountered, then the shorter wavelengths (UV, Violet, Blue) are scattered much more than the longer.

The molecules in air are smaller than sunlight wavelengths…shorter

wavelength blue light is scattered.

Water vapor molecules are larger than sunlight wavelengths…the view in fog is

degraded.



•  Absorption and Fluorescence –  If most of the light is absorbed within the glass, the

glass is opaque, and the energy from the light is converted into heat.

–  If an electron in the glass absorbs a photon of one particular wavelength and releases and transmits another longer wavelength and lower energy photon the glass has fluorescence.

•  Testing for tin side on float glass using UV light is an example.


Optical Properties of Glass Optics Definitions - Overview

•  Transmission •  Reflection •  Refraction

–  Dispersion –  Double Refraction

•  Distortion •  Gloss •  Color


Optical Properties of Glass Transparent Materials - Clear Glass Example

Visible (380-780nm)

Near IR (780-2500nm)

UV (<380nm)

Most Visible Light is transmitted.

Some UV & IR (and a small amount of

visible) is absorbed.

Some UV & IR (and a small amount of

visible) is reflected.


Optical Properties of Glass Transparency/Transmission

•  The passage of light through a material •  Light that is not reflected back to its source or absorbed is transmitted

through the glass •  Measured as a percentage of the original source light energy versus the

transmitted light energy •  Values vary with wavelength and material composition

–  For example, soda-lime glass has very low transmission at a wavelength of 265nm but fused silica transmits well at this wavelength.


Optical Properties of Glass Transmission Measurements

•  The amount of light transmitted is measured by a spectrophotometer. •  A monochrometer scans through a series of wavelengths and measures

how much light gets to the detector.

Monochrometer

Glass

Detector

Single Wavelength

Output


Optical Properties of Glass Transparency Visible

•  Clear glass is transparent, or, to be more accurate, partially transparent. –  Complete transparency would

imply no reflection and no absorption.

–  No glass achieves this uncompromised state, but most glass transmits some or most of the light that lands on it.


Optical Properties of Glass Transparency Selective Visible (Filters)

•  A number of glasses are selectively transparent. –  They transmit light of one

wavelength or color more efficiently than any other.

•  Normal green traffic light –  The lamp behind the green

lens supplies white light, or light that contains some light of all colors.

–  The green lens absorbs all colors except green which comes through the lens.

Wavelength


Optical Properties of Glass Transparency Visible Light (LED’s)

•  LED green traffic light –  The LED lamps project only in

the green part of the spectra. –  No filter or lens is needed to

absorb other wavelengths. –  LED’s are much more energy

efficient.

Wavelength


Optical Properties of Glass Transparency Selective UV and IR

•  Selectivity carries over into the ultraviolet and infrared regions. –  A number of special-purpose compositions have been designed

to transmit either ultraviolet or infrared while absorbing visible light. •  These glasses are black in appearance.

–  Some glasses are designed to absorb infrared and transmit visible—these heat-absorbing filters are found on film projectors.

•  The purpose of these filters is to get as much light as possible on the screen while keeping the film as cool as possible.

–  Ideal Low-E coatings would transmit as much visible as possible while eliminating (filtering) both UV and IR.


Optical Properties of Glass Transparent Materials

•  When light is incident on transparent materials, the electrons and atoms of the material begin to vibrate while the light propagates through the material.

•  If the frequency of the light matches the: –  Natural frequency of the electrons of the atoms in the material…

OR –  The vibrational frequencies of the atoms and molecules as a whole…

•  Then the light is absorbed. •  If these conditions are not met, then the light is transmitted.


Optical Properties of Glass Transparent Materials Example

•  Glass is made up of covalently bonded atoms (mainly Si and O).

–  The Si and O atoms possess electrons that have natural frequencies of vibration that closely match the frequency of ultra-violet (UV) light.

–  In addition, the Si-O bonded structure vibrates at lower IR frequencies. So if IR is present, it is also absorbed with the energy being dissipated as heat.

•  Visible radiation is sequentially absorbed, and then re-emitted from atom to atom.

•  Eventually, the visible light passes through the entire piece of glass.


Optical Properties of Glass Reflectivity and Reflection

•  Reflection is the return of light from a surface with no change in wavelength. •  Reflectivity is given as a percentage of the source light energy versus the

reflected energy and is dependent upon the angle of incidence. –  the angle between the light source and the glass surface)

•  Specified from “normal” (a line perpendicular to the glass surface) and by wavelength.


Optical Properties of Glass Reflection

•  Reflected light off of a shiny surface like a mirror obeys the law of reflection: –  The angle between the incident ray and the normal to the surface is

equal to the angle between the reflected ray and the normal.


Optical Properties of Glass Reflection •  Specular

–  When light obeys the law of reflection, it is termed a specular reflection.

•  Hard shiny surfaces are primarily specular in nature.

•  Even transparent glass specularly reflects a portion of incoming light.



•  Diffuse –  Diffuse reflection is typical of particulate substances like

powders. •  If you shine a light on baking flour, for example, you will not

see a directionally shiny component. •  The powder will appear uniformly bright from every direction.



•  Spread –  Many reflections are a combination of

both diffuse and specular components. •  Termed spread diffusion


Optical Properties of Glass Reflection and Mirrors

•  Reflectance from a glass surface can be regulated by coatings applied to the surface.

•  A metallic coating will produce the maximum reflectance—a first-surface mirror for instance.

•  When light reflects off of a rear surface mirror, the light first passes through the glass substrate, resulting in

–  reflection losses –  secondary reflections –  and a change in apparent distance.

•  First surface mirrors avoid this by aluminizing the front, and coating it with a thin protective SiO2 coating to prevent oxidation and scratching.


Optical Properties of Glass Refraction and Lenses

•  Refraction (or the bending of light) is caused by the light interacting with the charged particles in matter and traveling more slowly in transparent media than in air.

•  This change in speed of the light wave causes the wave to refract. •  The bending (or refraction) of light makes lenses possible.

–  Rays pass through are refracted by the lens and brought to focus at a single point.

•  A measure of the amount of bending is the refractive index. The higher the refractive index, the greater the bending.


Optical Properties of Glass Double Refraction (Birefringence)

•  The separation of a beam of light into two beams as it passes through a doubly refracting glass

•  Differing stress layers in a glass will cause birefringence, therefore birefringence may be used to measure the amount of stress in a material.

•  Can be visible in tempered glass (especially automobile rear windows). –  This is the way that heat-

strengthened and tempered glass is tested.


Optical Properties of Glass Absorption •  Amount of light energy converted to heat within a material that is not

transmitted nor reflected •  Absorption varies by material type and wavelength •  Tinted glass, due to the elements causing the color in the glass, will absorb

more light than clear glass.


Optical Properties of Glass Distortion •  Common in heat-treated glass

(to be discussed later) –  Roll Wave distortion –  Bow –  Warp

•  The glass transmits and reflects the same amount of light, however, because the glass is not flat, the optics are compromised.


Optical Properties of Glass Gloss

•  Gloss is a measure of the amount of reflected light from a surface reaching the observer versus the amount of light scattered by the surface.


Optical Properties of Glass Gloss

•  The lower the gloss unit number, the lower the glare and reflectivity of the glass surface.

•  Non-glare glass is commercially available from approximately 45 gloss units to 140 gloss units.

•  Due to the nature of processing, variations in the etch patterns will exist, commercially produced non-glare glass will have a gloss unit tolerance specified.

•  Some manufacturers limit the range of gloss units available due to equipment or market constraints.


Optical Properties of Glass Color in Glass •  Several mechanisms lead to color:

–  Absorption; electron transitions; Ligand field theory; redox equilibrium reaction. The Beer-Lambert Law

–  Light scattering; colloidal metal or semiconducting particles (Mie-scattering) –  Photosensitive glasses –  Fluorescence; lasers

•  Color results from selective absorption or scattering of specific (visible) wavelengths

–  Absorb red -> See blue; –  Absorb red & blue -> See yellow, etc.

•  If all visible wavelengths transmit equally: –  You'll see Clear → gray → black, depending on the total transmission (high →low)


+a

- a

+b

Optical Properties of Glass Color Measurements (CIE System)

•  Perceived color contains three components: –  Hue, Saturation, Lightness

•  This is the most commonly used color space and is based on perception of red, green and blue in the eye.

•  This results in three sets of signals being sent to the brain –  Light or dark, red or green and yellow or blue.

•  In the CIE L*a*b* system, color is modeled as a sphere. –  Brightness comprising the L*-axis linear

transform from white to black –  Hues modeled as opposing pairs on the a*/b*

axis, with saturation being the distance from the lightness axis


Optical Properties of Glass Color Measurements - CIE L* a* b* Color Space

•  L* = lightness of an object –  Ranges from 0 (black) to 100 (white)

•  a* = redness (positive a) or greenness (negative a)

•  b* = yellowness (positive b) or blueness (negative b)

•  The coordinates a and b approach zero for neutral colors (white, gray and black)

•  The higher the values for a* and b*, the more saturated the color is.

•  Color changes measured using ΔE*.

+a

- a

+b


Measuring Changes in Color (ΔE*)

•  ΔE* = √(ΔL*2+ Δa*2 + Δb*2) •  The human eye is very sensitive to changes away from achromatic

tones (a and b values near 0). –  May notice a difference between two 'shifted' grays that are as close as

0.5 ΔE apart.

•  ΔE* < 1 Highly-trained person cannot distinguish or see a color difference.

•  ΔE* from 1-2 Commercially acceptable color difference (A person may see a color difference)

•  A trained eye is capable of differentiating two colors that are closer to 3-4 ΔE apart

•  The average, casual viewer can notice the difference between two colors that are 5-6 ΔE apart.


Optical Properties of Glass Spectral Curves Transmittance

0

25

50

75

100

300

350

400

450

500

550

600

650

700

750

800

850

900

950

1000

1050

1100

1150

1200

1250

1300

1350

1400

1450

1500

1550

1600

1650

1700

1750

1800

Wavelength(nm)

%

Clear (3mm)

Clear (6mm)

Clear (12mm)

Green (3mm)

Green (6mm)

Green (10mm)

Gray float (6mm)

Blue (6mm)

Bronze (6mm)

UltraWhite (6mm)

•  Color of glass is defined by amount of visible light spectrum that passes through.

•  Note impact of thickness as well as type of glass.


Optical Properties Of Glass Iron Is The Main Cause Of Glass Coloration And Decreasing Transmittance

-a* 0

+ b*

green

yellow

red

blue -b*

+a*

Increase in Glass Thickness at Constant Iron Content

white

Increase in Iron Content at Constant Thickness


Optical Properties of Glass Why are Optics Important for Guardian?

•  Anything placed on the surface of glass or within glass will alter the optics.

•  Tinted and low-iron glass are not just aesthetically pleasing, but perform differently than clear glass due to the laws of optics.

•  Low-E and Reflective coatings are highly engineered filters that are applied to the glass to alter the optical properties. –  Absorb UV and IR light. –  Transmit as much visible light as possible. –  Remain color neutral as to be aesthetically pleasing.

•  An understanding of optics assists in the understanding of common glass and window terminology.


IV – The Float Glass Process


The Float Glass Process Overview

•  Developed in late 1950 into 60’s by Sir Alistair Pilkington •  Glass is melted conventionally but formed by floating on molten tin •  Continuous Process

–  (24hours – 7days/week – Years) •  Few discrete process steps •  Very energy intensive •  Not complicated but complex •  Relatively indirect process control

methods •  Very high product quality requirements


The Float Glass Process Raw Materials Review

•  Main constituent = sand. •  Sand can be fused to produce glass

but the temperature at which this can be achieved is very high (about 1700°C [3100°F]). –  Adding other minerals and chemicals

to sand can considerably reduce the melting temperature and reduce cost.

•  The addition of sodium carbonate (soda ash), to produce a mixture of 75% silica and 25% of sodium oxide, will reduce the temperature of fusion to about 800°C (1475°F). –  However, a glass of this composition is

water-soluble and is known as water glass.


The Float Glass Process Raw Materials Review

•  In order to give the glass workability and chemical stability, limestone and dolomite are needed.

•  In the float glass process, Cullet (broken scrap glass) is added to accelerate melting and reduce the energy required to melt the batch.


PYROLYTIC COATING

The Float Glass Process Overview


The Float Glass Process Batch House

•  Raw materials arrive by truck or rail.

•  Materials are tested & unloaded.

•  Materials dispensed, weighed according to batch formula.

•  Batch is checked & mixed. •  Mixed batch is sent to furnace

hopper. •  Cullet added to final mix prior

to melting.


The Float Glass Process Melting Furnace

•  Batch introduced by charger •  Batch forms logs which melt and move

via convection and pull. •  All materials melt and homogenize with

time and temperature. •  Temperature control is critical for

production, as well as safety. •  Gases are released and bubbles rise out

of melt with time and temperature.


The Float Glass Process Melting Furnace Design •  Furnace is made of refractory bricks

supported by steel super structure. –  Melter furnace (container) –  Regenerators (combustion)

•  Furnace is designed for maximize output.

•  Roughly 30 feet wide & 160 feet long. •  Holds in excess of 1000 tons of molten

glass. •  Burners are located above the glass.


The Float Glass Process Melting Furnace - Furnace Construction


The Float Glass Process Melting Furnace Batch Charging


The Float Glass Process Melting Furnace Glass Furnace


The Float Glass Process Melting Furnace - Convective Flows

•  Temperature differences drive flows.

•  Heat moves to displace cold (creates a thermal equilibrium).

•  Glass moves in accord with heat. •  Thermal action also drives

chemistry. •  Refining agents create spring

zone at location of max furnace temperature.

•  Glass pull also drives flow patterns.


The Float Glass Process Refining Zone

•  More than 15% of a glass batch is gas in the form of carbonates, water or entrapped air.

•  Gas inclusions (bubbles) are defects and must be removed.

•  Refining of glass occurs when sulfate in glass is thermally driven to SO2 gas at the hottest part of the process.

•  SO2 fills existing bubbles causing them to grow and accelerating their rise.

•  2SO3 (glass) -> 2SO2 (bubble) + O2 (glass)

υ = (4/3)πa3(ρ’- ρ)g = 2 a2g(ρ’- ρ)

6 πηa 9 η


The Float Glass Process Cooling Zone Working End

•  The working end area of the process is where glass is brought to a uniform temperature before forming.

•  Glass flows from the refining end of the furnace, through the canal where it is skimmed, cooled and stirred.

•  Glass flows and temperatures need to be very stable in order not to disrupt the homogeneity of the melt.

•  The glass then travels to the canal (A channel where the glass is allowed to pour into the tin bath).

Waist Coolers &

Stirrers

Canal Connects Furnace to Tin Bath


The Float Glass Process Tin Bath

•  Pouring molten glass onto molten tin allows it to spread, flatten and be formed into a continuous glass sheet, called a ribbon.

•  Attenuators or top roll machines, grip the ribbon and enable it to be worked (stretched, or pushed).

•  Again, temperature control and uniformity are the key to controlling and producing a high quality ribbon.


The Float Glass Process Tin Bath

Attenuators

Lift out rolls Canal


The Float Glass Process Why Use Tin?

•  A suitable support for the glass must be: –  Liquid from 1000°F (540°C) to 2000°F

(1100°C). –  Denser than glass. –  Have a relatively low vapor pressure. –  Be relatively un-reactive with glass.

•  Only metals are suitable.

–  Gallium, tin and indium are possible. •  Only tin is cost effective.

Sulfur in FuelOil

Salt Cake (Na SO ) inBatch

Sulfur Compounds inGlass (SO )

Sulfur Dissolvedin Tin

Stannous Sulphide (SnS)Vapour in Atmoshere

Deposits on Roof, Coolers,Etc.

H S in Bath Atmoshere

Tin on the Ribbon(Top Speck)

+ Tin BottomSurface

Volitilazation

Cools Condensation

As Temp Increases

+ H

+ H Top Surface2

2

3

2 4

2

+ H2

+ Sn


The Float Glass Process Annealing Lehr •  Annealing is a controlled cooling profile that allows

the release of stresses that build up in the glass ribbon.

•  Glass begins to fully solidify (930°F-1100°F). •  Glass cooled to 350°F or less. •  Temperature closely controlled to relieve stress. •  Proper annealing is important because:

–  Transient stresses can cause on-line breakage. (X-breaks, splits).

–  Too high stresses can create on-line cutting problems. (Poor breakout).

–  Improper residual stress profile can cause off-line (customer) cutting problems (Bad scores, bad edges, etc.).

•  Lehr operations can also influence ribbon shape. (Warp and or bow and dish profiles)


The Float Glass Process Residual Stresses

•  Residual stress is the stress leftover after annealing. It is important because it can impact how glass cuts at a customer’s location.

•  Stress is measured using an optical device called a compensator. It gives a measure of the internal tension. High tension also means high surface compression.

•  Too much compression and the glass break will not follow the score resulting in bad edges and a non-square cut size.


The Float Glass Process Cold End Operations Inspection/Defect Detection

•  Float glass quality requirements are among the most restrictive in the glass industry.

•  The defects now being rejected can no longer be seen by eye without assistance.

•  Lasers or high resolution camera systems are now used to locate and in many cases categorize types of defects online.

•  Glass cutting routines now enable yield optimization by cutting around defects.


The Float Glass Process Cold End Operations Inspection/Defect Detection

•  All glass contains defects at some level. Glass specifications such as ASTM C1036 set maximum size and frequency limits upon what is permissible. –  Application Specific


The Float Glass Process Cold End Operations Other Activities

•  Cold end operations comprise all activities after the annealing and cooling sections of the lehr and include: –  On-line washing (at some locations), –  On-line defect detection (laser or

camera), –  Cutting and trimming, –  QC inspection and data basing, –  Anti-stain separator application, –  Either manual or automatic packing, –  Close-up, tagging and warehousing, –  Shipping


The Float Glass Process Cold End Operations


The Float Glass Process Interesting Facts

•  A glass furnace producing 500 tons per day contains 1,600 tons of glass at all times.

•  A 500 ton per day glass furnace will produce 54,750 miles of glass during its 15 year lifetime. (Enough to circle the earth 2.3 times, if left uncut.)

•  A furnace uses 7.2 MM cu. ft. of natural gas in a day, enough to heat 14,400 homes per day.

•  The process uses enough electricity to power 6,700 homes and enough water to supply 667 homes for a day.

•  The tin bath holds over 170 tons of molten tin metal. •  If left uncut, a ribbon of glass would run approx. 12 miles in a 24 hour day.


V – Float Glass Products


Float Glass Products Clear Float Glass

•  Clear float glass offers excellent optical properties and clarity, transmitting up to 90% of the sun’s visible spectrum.

•  Can be further fabricated into reflective, low-E, laminated, security, insulating, heat-treated and ceramic decorated applications.

•  Available in a wide variety of widths and thicknesses. –  Thickness: 1.7mm – 19mm –  Up to ~4m wide

Window Shower door

Mirror


Float Glass Products Clear Monolithic Glass - Spectral Diagram

%


Float Glass Products Tinted Glass or Heat-Absorbing Glass

•  Tinted glass (or body-tinted glass) is made by adding various colorants to the normal clear batch.

•  Tinted glass absorbs more solar radiation than clear float glass.

•  The tint reduces the transmission of infrared, visible and ultraviolet light rays. –  Transmission can vary from 14 to 85%

depending on color and thickness. •  As a result, the energy efficiency of air-

conditioning equipment for a building glazed with tinted glass can be improved.


Float Glass Products Tinted Glass •  Performance and Advantages

–  Interception of solar radiation •  Reduces the energy consumption of air-

conditioning facilities. –  Glare prevention

•  Reduces the glare by absorbing certain amount of light rays in the visible spectrum.

–  Discoloration resistance •  Absorbs certain amount of ultraviolet

rays to retard discoloration of furniture and goods indoors.

•  Applications –  Commercial and civil buildings –  Interior decoration –  Show windows –  Automobile glass


Float Glass Products Tinted Glass - Various Colors

Transmittance

0

25

50

75

100

300 350 400 450 500 550 600 650 700 750 800

Wavelength(nm)

%

ClearGreenBronze floatGray floatPPG Azuria®


Float Glass Products Low Iron Glass Definition and General Requirements •  Definition: “a highly transparent

colorless glass due to low content of iron in glass”

•  Transparency –  Measured and determined as

visible light. –  Transmittance (%Lta (D65), Ltc,

L*, Tvis).

•  Color –  Measured and described by

color values a*, b*


Float Glass Products Color Measurements - CIE L* a* b* Color Space

•  L* = lightness of an object –  Ranges from 0 (black) to 100

(white).

•  a* = redness (positive a) or greenness (negative a)

•  b* = yellowness (positive b) or blueness (negative b)

•  The coordinates a and b approach zero for neutral colors (white, gray and black).

•  The higher the values for a* and b*, the more saturated the color is.

+a

- a

+b


Float Glass Products Standard Clear Glass Not Clear

Standard Clear Glass (6 mm)

0

20

40

60

80

100

250 750 1250 1750

wavelength, nm

% T

rans

mitt

ance

High Transmittance Clear Glass (6 mm)

020406080100

250 750 1250 1750

wavelength, nm

% T

ran

sm

itta

nce

Transmittance <89% (at 6 mm)

Green edge color Increased coloration and

loss of transmittance with thickness


Float Glass Products Standard Clear Glass is Not White?

-a*

green

yellow

+b*

0 -1 -2

blue

-b*

red

+a*

•  Standard glass has a green tint. •  White glass is virtually colorless.


-a* 0

+ b*

green

yellow

red

blue -b*

+a*

Increase in Total Iron Content at Constant Thickness

Increase in Ferrous Content at Low Total Iron

Float Glass Products Main Cause of Coloration and Low Transmittance in Clear Glass: Iron


Float Glass Products Solar Glass

•  Definition: “a low iron glass, flat or patterned, having high visible light transmittance and high transmittance of solar energy (both ~91% at 3- 4 mm)”

•  “Low iron” means: –  Total iron, Fe2O3 (0.01 to 0.02% ) –  Low ferrous, FeO (0 to 0.004% )

•  Clear Glass –  0.08 to 0.11% Fe2O3 –  0.016 to 0.024% FeO

•  Visible light transmittance, %Tvis (Lt D65) –  Measured in the wavelength range from 380 to 780 nm (ISO 9050) –  Strongly depends on total iron content as well as ferrous in glass

•  Solar energy transmittance, %Tsol –  Measured in the wavelength range from 305 to 2537 nm (ISO 9050) –  Dominated by ferrous in glass


Float Glass Products Low-Iron Glass Solar/Optical Properties & Spectral Graph

Spectra of clear and low iron glasses

0102030405060708090

100

300 800 1300 1800 2300wavelength

%Tra

nsmi

ssion

ClearExtraClearSolar

Tvis

Tsol

Solar glasses have Tsol>91% and Tvis>91% at 3-4 mm. It is not enough to have low iron in glass – it has to be highly oxidized

to perform as a solar product.


VI – Solar Performance and Common Terminology


Solar Performance and Common Terminology Surface Numbers

•  Method –  Always start from the outside with #1 –  Increment the surface number as you move from one bulk material to another

•  e.g. from glass to air or from glass to PVB


Surf

ace

1

EXTERIOR

Double Insulated G

lass

Surf

ace

2

Surf

ace

3

Surf

ace

4

Surf

ace

1 EXTERIOR

INTERIOR

Monolithic

Surf

ace

2

INTERIOR


EXTERIOR EXTERIOR

INTERIOR

Surf

ace

1

Surf

ace

2

Double Lam

inated Surf

ace

3

Surf

ace

4

Surf

ace

5

Surf

ace

6

Double Insulated

Surf

ace

7 Su

rfac

e 8

PVB PVB

Surf

ace

1

Surf

ace

2 Su

rfac

e 3

Surf

ace

4

Surf

ace

5

Laminated (O

utboard) Double Insulated

PVB

Surf

ace

6

INTERIOR


Solar Performance and Common Terminology Typical Thermal Properties of Glass Clear 6mm Monolithic


UV(300-380nm)

2%

Near IR(780-2500

nm)49%

Visible(380-780nm)

49%

UV VIS Near (Solar) IR Thermal IR →

20 C ~ 10,000 nm


Solar Performance and Common Terminology Clear Monolithic Glass Spectral Diagram

%


Solar Performance and Common Terminology The First Rule Of Optics

•  REFLECTION •  TRANSMISSION •  ABSORPTION •  R (%) + T (%) + A (%)= 100% •  ALWAYS !!!


Solar Performance and Common Terminology Visible Light Transmittance


Solar Performance and Common Terminology Visible Light Transmittance

•  The percentage of visible light (380-780nm) within the solar spectrum that is transmitted through glass.

~90% for clear glass

EXTERIOR INTERIOR


Solar Performance and Common Terminology Visible Light Reflectance

Indoor Reflectance is the light from the interior of the building reflecting back in.

Outdoor Reflectance is that of the outdoor light reflecting out.

These numbers can be quite different when coatings and glass layers (IG and Lami) are added to the model.


Solar Performance and Common Terminology Visible Light Reflectance

•  Reflection only happens at interfaces •  The percentage of visible light (380-780nm) within the solar spectrum that is

reflected from the glass surface

Total of ~8% of visible light for CLEAR 6mm Glass is REFLECTED.

(~4% from each surface)

EXTERIOR INTERIOR


Solar Performance and Common Terminology Visible Light Absorption

% Visible Absorb ----- 2.9% ----- 89% Trans.


Solar Performance and Common Terminology Visible Light Absorption

The absorption of wavelengths between 380-780nm

Visible (380-780nm)

2.9% Visible light for CLEAR 6mm glass is ABSORBED.


Solar Performance and Common Terminology Solar Energy Direct Transmittance


Solar Performance and Common Terminology Solar Energy Direct Transmittance

•  The percentage of ultraviolet, visible, and near infrared energy within the solar spectrum (300-2500nm) that is transmitted through the glass.

Visible (380-780nm)


UV (<380nm)

~62% Near IR Transmitted

89% Visible Transmitted

63% of UV Transmitted

EXTERIOR INTERIOR

79% Total solar energy for

CLEAR 6mm glass is

TRANSMITTED.


Solar Performance and Common Terminology Solar Energy Reflectance


Solar Performance and Common Terminology Solar Energy Reflectance

•  The percentage of ultraviolet, visible, and near infrared energy within the solar spectrum (300-2500nm) that is reflected from the glass surfaces.

EXTERIOR INTERIOR

Visible (380-780nm)

UV (<380nm)

7% Total Solar Energy for

CLEAR 6mm glass is

REFLECTED.

8% of Visible is Reflected

~6% of Near IR Reflected

7% of UV is reflected.


Solar Performance and Common Terminology Solar Energy Absorption

% Solar Absorb ----- 14.1 ----- 79% Trans.


Solar Performance and Common Terminology Solar Energy Absorption

Visible (380-780nm)


UV (<380nm)

INTERIOR

2.9% Visible Absorbed

30.3% UV Absorbed

30.3% IR Absorbed

14% Total Solar Energy for CLEAR 6mm glass is

ABSORBED.

The absorption of all wavelengths between 300-2500nm


Solar Performance and Common Terminology Solar Heat Gain Coefficient (SHGC)


Solar Performance and Common Terminology Solar Heat Gain

•  Solar heat gain includes directly transmitted solar energy and absorbed solar radiation, which is then reradiated (emitted), conducted or convected into the space as heat.

Visible (380-780nm)


UV (<380nm)

EXTERIOR INTERIOR

Absorbed energy in the

glass becomes heat (IR).


Solar Performance and Common Terminology Solar Heat Gain Coefficient (SHGC)

•  The ratio of the solar energy passing through the window to the incident solar energy

•  The lower the SHGC, the less solar heat it transmits –  U.S. Solar Heat Gain Coefficient uses an air mass of 1.5 –  For warm climates, a SHGC should be 0.40 or less

•  Similar European term is g-value; –  This is the percentage of total solar energy (direct and indirect) transferred

though the glass. –  The g-value uses a solar air mass of 1.0.


Solar Performance and Common Terminology Solar Heat Gain

Solar Heat Gain

Direct Solar Transmittance

Indirect Re-Radiation = +


Solar Performance and Common Terminology Shading Coefficient (SC)


Solar Performance and Common Terminology Shading Coefficient (SC)

•  The ratio of the solar heat gain through a specific glass product to the solar heat gain through a lite of 1/8 in. (3mm) clear glass.

•  The shading coefficient of a glass product is calculated as follows:

•  The definition gives 3mm clear glass a SC of 1.0 •  Equivalent European term is b-value.

0.87SHGC

Glass Clear mm 3 of Gain Heat SolarQuestion in Product of Gain Heat Solar SC ==


Solar Performance and Common Terminology U-value Winter Night & Summer Day)


Solar Performance and Common Terminology U-value (Winter Night & Summer Day)

•  U-factor - A measure of air-to-air heat transmission (loss or gain) due to the thermal conductance and the difference in indoor and outdoor temperatures of a 39” (1m) high glazing. Referred to as the overall coefficient of heat transfer.

–  Winter-night = 12.3 mph wind at -0.4°F & 69.8°F indoors.

–  Summer-day = 0 sun, 6.15 mph wind at 89.6°F & 75.2°F still indoor air.

•  English Units are Btu/hr•ft²•F. •  As the U-value decreases, so does the amount of

heat that is transferred through the glazing material. The lower the U-value, the more restrictive the window is to heat transfer.

•  The U-value is the reciprocal of the R-Value.


Solar Performance and Common Terminology R-Value

•  The thermal resistance of a glazing system expressed in ft2/hr/°F/Btu (m2/W/°C).

•  The R-value is the reciprocal of the U-value (1/U).

•  The higher the R-value, the less heat is transmitted throughout the glazing material.

•  Used commonly in regard to walls, roofs and insulation rather than fenestration.


Solar Performance and Common Terminology R-Value

R-Value Winter Night Air 0.189 0.032 Air 0.754 0.975 R total


Solar Performance and Common Terminology U-value (K-Value) (Winter Night & Summer Day)

•  In Europe, the U-value is calculated using different surface coefficients, inside 8W/m2K (no wind), outdoor 23 W/m2K (assumed wind speed).

•  Standard Conditions: 10°C gap temperature, 15°C difference between inside and outside.

•  European units are W/m2K.


Solar Performance and Common Terminology Relative Heat Gain (RHG)


Solar Performance and Common Terminology Relative Heat Gain (RHG)

•  The amount of heat gain through a glass product taking into consideration the effects of solar heat gain (shading coefficient) and conductive heat gain (U-value).

•  RHG = [(Summer U-value) x (89.6°F - 75.2°F)] + [(Shading Coefficient) x (200 Btu/hr•ft2)]

•  Units are Btu/hr/ft2 (W/m2).


Solar Performance and Common Terminology Hemispherical Emittance

Hemi Emittance

0.837

0.837

Will change drastically with a Low-E coating. For instance, adding a double silver low-e coating to Surface #2 drops emittance on surface #2 to 0.039.



•  The capacity to emit or radiate heat off of a surface. •  Low-E glass has a coating on it that reduces the rate of heat

escaping, giving the glazing a better U-value (or R-Value). •  Hemispherical emittance accounts for heat radiating from all

directions off surfaces. •  E=1-R •  R is reflection at thermal wavelengths

–  2,500 to 50,000 nm

•  In EU, “emissivity” is the term for “emittance”, and “corrected” is the term for “hemispherical”.


Solar Performance and Common Terminology Emittance


Solar Performance and Common Terminology Light to Solar Gain Ratio (LSG)


Solar Performance and Common Terminology Light to Solar Gain Ratio (LSG) (Selectivity)

•  LSG = Tvis / SHGC •  Example: SN54 LSG = 0.54/0.28 = 1.90

•  This ratio is helpful in selecting glazing products for different climates in terms of those that transmit more heat than light and those that transmit more light than heat.


Solar Performance and Common Terminology Light to Solar Gain Ratio (LSG) (or Selectivity)

0

0.5

1

1.5

2

2.5

3

3.5

4

0 1 2 3 4 5 6Number of Silver Layers

LSG

This is real data from our coatings


Solar Performance and Common Terminology Color Rendering Index


Solar Performance and Common Terminology Color Rendering Index (CRI)

•  A method for describing the effect of a light source on the color appearance of objects, compared to a reference source.

–  Sunlight (in the case of glass and windows) of the same color temperature (CCT).

•  In a day lighting context, the color rendering index defines the spectral transmissive quality of glasses or other transparent materials.

•  Examples –  Tungsten bulb & Sunlight/Blue Sky = 100 –  High Quality Fluorescent = 90 –  Green Glass = 80

•  Between 80-90 -> Good •  90-100 -> Very Good •  Museums typically specify 95 or higher.


Solar Performance and Common Terminology UV Transmittance and Absorption, Damage Weighted Transmission

% UV Absorbed ----- 30.3 ----- 62.78 UV Trans.

Tdw = 81.1

Tdw-K = 66.2


Solar Performance and Common Terminology UV Transmittance

•  The percentage of ultraviolet energy within the solar spectrum (300-380nm) that is transmitted through the glass.

~63% UV Transmission

EXTERIOR INTERIOR


Solar Performance and Common Terminology UV Absorption

•  The absorption of wavelengths less than 380nm.

UV (<380nm)


Solar Performance and Common Terminology Damage Weighted Transmission (Tdw)

•  Tdw- ISO shows the potential harm that transmitted light has on furnishings. The higher the number the greater the chance that the interiors of a building will fade due to the glass in the windows.

•  Tdw-K is related but is more out-dated.


Solar Performance and Common Terminology Clear Monolithic Glass Spectral Diagram

%


Solar Performance and Common Terminology Clear Double Insulating Glass Spectral Diagram


Solar Performance and Common Terminology Clear Triple Insulating Glass Spectral Diagram


Solar Performance and Common Terminology Terms We have Covered

Visible Solar Conductivity Combined Effect

T Rindoors

Routdoors

T Routdoors

SC SHGC

U-factor R-factor

RHG

Europe b-value g-value

Emissivity Selectivity Appearance Ultraviolet

ε LSG CRI UV trans Tdw


VII - Secondary Glass Processing (Non-Sputtered Films)



•  The capacity to emit or radiate heat off of a surface. •  Low-E glass has a coating on it that reduces the rate of heat

escaping, giving the glazing a better U-value (or R-Value). •  Hemispherical emittance accounts for heat radiating from all

directions off surfaces. •  E=1-R •  R is reflection at thermal wavelengths

–  2,500 to 50,000 nm

•  In EU, “emissivity” is the term for “emittance”, and “corrected” is the term for “hemispherical”.


Secondary Glass Processing (Non-Sputtered Films) Pyrolytic Coatings -Introduction

•  Chemical Vapor Deposition (CVD) Process •  Performed in-line on the float glass line •  Chemical coating is bonded to the glass

while it is in a semi-molten state –  Polycrystalline layer of tin-oxide –  Transparent since the tin oxide grains are

smaller than visible light

•  Chemical compound becomes a part of the glass surface

•  Also called “Hard-Coat”


Secondary Glass Processing (Non-Sputtered Films) Pyrolytic Coatings - Introduction

•  Pyrolytic Film Properties –  Durable (mechanically and chemically) –  Long shelf-life –  Temperable without appearance change –  Less susceptible to scratching –  Bendable (within limits) –  Fabrication friendly –  Moderate low-E performance

•  Can be placed on the exterior (#1 or #4) surface. •  Can be used monolithically •  Limited performance •  Limited variety •  Usually used with heat absorbing (tinted) glass to improve

performance •  Haze can sometimes be visible during bright sunlight


Secondary Glass Processing (Non-Sputtered Films) Pyrolytic Coatings - Process Overview


Secondary Glass Processing (Non-Sputtered Films) Pyrolytic Coatings Process Diagram


Secondary Glass Processing (Non-Sputtered Films) Pyrolytic Coatings - Uses

•  Residential and commercial glazing applications •  Areas of the world where soft-coat (sputtered) coatings may be too delicate •  Suitable for climates where passive solar heat gain is a benefit •  Technical applications such as refrigerator and oven doors.


Secondary Glass Processing (Non-Sputtered Films) Ion Beam Coating - Overview

•  Linear Ion Source Theory and Uses •  Ion Beam Products

DiamondGuard deposition in Corsicana G9 coater

CoDep lab coater at STC.


Secondary Glass Processing (Non-Sputtered Films) Linear Ion Source

•  Developed in Russia for space propulsion •  Optimized by Guardian for materials processing •  First production units supplied by Advanced Energy •  Low Cost version in test •  Similar physics as planar magnetron

–  Scaleable, compatible –  with MSVD coaters –  Uniform, high energy beam –  No targets, lower costs


Beam

Len

gth

38 cm

96 cm

150 cm

3.0 m

SWRI Corsicana G-9

Thalheim Bascharage GLC

DeWitt PPC

Vactec STC – CoDep, ILC

3.7 m

Secondary Glass Processing (Non-Sputtered Films) Ion Beam - Development History

1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010

Bascharage Coater II Porto Real


Ar + - DC Power

CxHy+ 1500 eV

C2H2

Secondary Glass Processing (Non-Sputtered Films) Ion Beam Deposition

•  Benefits –  High energy – good adhesion and dense, hard deposits –  Low gas flow load – compatible with existing large area MSVD systems –  Background gas mode – permits extended operation between vents

•  Guardian’s production beams permit deposition on an unprecedented scale.

•  This deposition method is used to produce Guardian DiamondGuard and ShowerGuard products.


VIII – Secondary Glass Processing (Sputtered Films)


Light Waves

fλnc v ==

Wavelength (nm)

Amplitude

2211 λnλn =

fh E =

21 ff =At an interface:

v: velocity of light in a material n: index of refraction of a material f: frequency of light λ: wavelength of light E: energy of light c: speed of light in a vacuum (3x108 m/s) h: Planck’s constant (6.626x10-34 Js)


Color Perception

•  Perception depends on: 1) Light Source (sunlight, fluorescent, CIE-C, etc) 2) Object 3) Observer (CIE 2 deg, etc)


Defining Color

•  CIE L*, a* and b*

–  Coordinate system –  Standard of measurement

•  L* describes the lightness •  a* and b* describe hue

•  a* is red (+) vs. green (-) •  b* is yellow (+) vs. blue (-)

- Can be translated to/from RGB, CMYK, HSL, xyY, etc.

+ a*

+b*

-b*

- a*

L = 100

L = 0


Light And Solids

•  How do we modify the behavior of glass to make windows conserve energy and look different or the same?

•  Answer: Change the interaction between the glass and light using coatings to modify:

Reflection / Transmission

Absorption

Interference


The First Rule Of Optics

REFLECTION TRANSMISSION ABSORPTION

R (%) + T (%) + A (%)= 100%

ALWAYS


Absorption •  If electrons are free to move, then

–  the material conducts AND –  the electrons “drift around”

absorbing light •  So, generally speaking, good

electrical conductors are bad at allowing light through (opaque).

•  What doesn’t get absorbed gets reflected or transmitted.

–  Remember T+R+A=1

•  Examples: –  Opaque: Aluminum, Iron, Silver –  Transparent:: Glass, Plexiglas

•  Most objects get color from simple reflection / absorption

–  So why are so many non-conductive things opaque??

–  Answer: “Contaminants” or other small amounts of “conductive” material

•  Iron content is the main difference between Clear and ExtraClear

e -

MATERIAL LIGHT


Why Do We Use Silver ?

•  Most conductive metal –  Highest IR reflectance (lowest emissivity) for a given thickness of material. –  Highest transmission for a given thickness.

•  Color Neutral –  Gold and Copper absorb more heavily in the visible and lose transmission.

•  This results in intense color not suitable for residential/commercial applications.


Transmission of Perfect Low-E Filter

0

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Wavelength, nm

Tran

smis

sion

, Ref

lect

ance

, %

T-Ideal

Visible Near-IR Far-IRUV


Actual Transmission Typical Low-E Filters Double Silver vs. Single silver Transmission

0

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300 500 700 900 1100 1300 1500 1700 1900 2100 2300 2500

Wavelength, nm

Tran

smis

sion

, Ref

lect

ance

, %

Double Silver - Narrower, steeper walls, greater IR cut-off, Solar Heat Gain Coefficient

Double Silver - Wider transmission near the peak area for more neutral transmitted color

Single Ag

Double Ag

— Single Silver

— Double Silver


Reflection of Perfect Low-E Filter

05

101520253035404550556065707580859095

100

300

800

1300

1800

2300

Wavelength, nm

Tran

smis

sion

, Ref

lect

ance

, %T-Ideal

Visible Near-IR Far-IRUV


Actual Reflection, Typical Low-E Filters Double Silver vs. Single Silver Reflectance

0

10

20

30

40

50

60

70

80

90

100

300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000 2100 2200 2300 2400 2500

Wavelength, nm

Tran

smis

sion

, Ref

lect

ance

, %

F-RLE7036F-PPII

Double Silver -Lower, wider, more neutral reflectance

Double Silver - Steeper walls, more near-IR reflection

Double Silver - More Ag in layer stack yielding more far-IR reflectance (lower emittance: better U-value)

— Single Silver

— Double Silver


Introduction to Sputtering Thermal Evaporation


What is a Vacuum and Why is it Important?

Why? •  Control the material being deposited - Silver works great, but Silver Oxide is

terrible. •  Allow for efficient plasmas. •  Allow material to travel from the source to the glass.

Vacuum is the absence of mass; absence of air. Measure vacuum based on pressure which is proportional to the number of molecules. Sputtering pressure is about 1 millionth of atmospheric pressure.

In air, the mean free path of a molecule is 300 A = 3x10^-8 m. In a sputtering system, the mean free path of molecules is 3x10-2 m. Mean free path on a pool table full of balls is about 4 ft, the pool table would be about 1000 miles long for the balls to have the same increase in mean free path as do molecules in a sputtering chamber.


Introduction to Sputtering Process Theory •  Similar to EVAPORATION, but uses a momentum transfer approach. •  Imagine billiards. You hit the cue ball and it hits the other balls and they

move. –  Sputtering is the same. A ball (gas ion) is accelerated towards the metal target.

When it strikes the target, atoms are dislodged and some are removed. These atoms condense on the substrate (glass, chamber walls, etc…)


Introduction to Sputtering Process Theory •  What is an ION ?

–  An Ion is a charged atom or molecule. •  Atoms are made of a central core and surrounding electrons. The core is a proton

(positive charge) and the surrounding electrons have a negative charge. The number of protons = the number of electrons in an atom.

•  In an ion, a charge occurs because an electron has been removed. This ion is positively charged.

•  Ions can also gain an electron and have a negative charge.

+ -


Introduction to Sputtering Process Theory •  How do we make “ions”?

–  In a vacuum, an electric current is applied across two electrodes. One electrode is negatively charged (cathode) and one is positively charged (anode)

–  When a gas is placed in the space between the electrodes the electrons collide with the gas and knock electrons off – thus creating the ions !!

Electrons move from the cathode to the anode. (negative to positive)


Introduction to Sputtering Non-reactive magnetron sputtering

Metal Target Cathode (-)

Metal Coating

Argon gas inlet

Anode (+)

Argon Ion (+)

Metal Atoms Plasma or

Ionized Gas

Magnet Magnet

Glass

Electron (-)


Introduction to Sputtering Cylindrical Magnetron Sputtering


Planars vs. C-mags

•  C-mags are round and they rotate, planars are flat and stationary

•  Planars - lower initial cost •  C-mags - better target utilization

•  Uniform use of the entire rotating target

•  C-mags - much higher deposition rate (better cooling) •  C-mags - hard to manufacture for some materials

(ex. silver) C-MAGS

PLANAR


Introduction to Sputtering Cylindrical Magnetron Sputtering


Introduction to Sputtering Entry & Exit Vacuum Locks

COATING BAYS

GLASS TRANSPORT

Besides layer thicknesses and associated deposition rates and coating bays, entry and exit lock pumping can often be process rate limiting.


Introduction to Sputtering Porto Real Coater Layout •  The layout is designed based on the products that will run on the coater:

–  Layer thicknesses and deposition rates

Ion

Bea

m

Rea

ct

Rea

ct

Rea

ct

Ion

Bea

m

Met

al

Met

al

Met

al

Met

al

Met

al

Rea

ct

Rea

ct

Rea

ct

Rea

ct

Rea

ct

Etch Si Si Si DLC NbZr NiCr Ag NiCr NbZr Si Si LID Zr ZrSi3N4 Si3N4 Si3N4 NbZr-O NiCr NiCr NbZr-O Si3N4 Si3N4 ZrOx ZrOx

Sputter chamber 1

Mai

nten

ance

Val

ve

1514

5

13 25

10 1411

Mai

nten

ance

Val

ve

32 33 34 35

13 1512

23

8

Mai

nten

ance

Val

ve

31

Mai

nten

ance

Val

ve

11

321

12

7

22

9

24

Sputter chamber 3

21

Sputter chamber 2

64


IX – Glass Fabrication


Glass Fabrication Overview

•  To provide insight on glass cutting, edge-work, and general fabrication

•  Develop awareness of general handling and fabrication practices •  Provide a basic understanding of heat-treated glass types and

processes –  Heat-Strengthened, Tempered, Heat-Soaked

•  To understand the differences between various types of furnaces •  To explain spontaneous breakage •  To explain the general principles of bending


CNC Glass Cutting And Laser Marking System

Manual Cutting Automated Machine Cutting

Click to launch glass cutting


Universal Cutting Table Guidelines

•  The cutting-table surface must be frequently cleaned to reduce the potential for abrasion by glass fragments.

–  The cutting surface should be thoroughly vacuumed throughout a campaign •  The cutting-table surface must be carefully monitored for damage and

should be replaced when the nap becomes uneven or overly compacted. •  The air system must be carefully monitored for pressure and even coverage

across the table. –  Air lines must be free of contaminants such as hydraulic fluid.

•  Coated surface detection is mandatory prior to all fabrication steps and the coated surface must face during up during horizontal transfer and cutting.

–  There must be no contact with the coated surface during cutting, except by the cutting wheel.

•  Cutting oil must be approved for use with coated products, and always used in moderation.

–  These fluids evaporate quickly and leave behind no residue that could contaminate the washers.


Manual Breakout

Glass Break-Out

•  Following the cutting process, glass break-out must be performed in a manner that ensures good edge quality and minimizes contact with the coated surface.

•  Proper gloves must be worn at all times and they must be clean and dry. Glass fragments, perspiration, oil and other contaminants can damage the coating.


Automated Breakout

Glass Break-Out

•  Automated breakout systems must be properly maintained and adjusted to glass size and thickness.

•  Manual breakout must be performed one lite at a time and glass must never be stacked. –  Care must be taken to avoid sliding or rubbing one pane of glass

against another.


Glass Seaming

•  Glass seaming, also known as swiping or arrissing, involves the use of grinding belts to remove the sharp edges that result from the cutting process.

•  Seaming glass prior to heat-treatment reduces mechanical stress and improves process yield.

•  Glass seaming may be performed using a dry or wet process.

Manual Seaming Station


Glass Seaming

•  The seaming table surface and conveyor rolls must be cleaned frequently.

•  The condition of the seaming belts must be inspected regularly to ensure optimum edge quality.

•  Contact with the coated surface must be avoided during seaming. Contact must be made from the edges or with the uncoated surface of the lite.

Automated Seaming Process


Glass Fabrication Machine Edging and Grinding •  Accomplished using grinding and polishing wheels •  May be performed for tempered or heat-strengthened

applications before heat-treatment –  Automotive Glass –  Mirrors –  Glazing with exposed edges –  Backboards –  Hockey glass –  Shower doors –  Furniture & Appliances

•  Can range from simple seamed edges to complex ground, polished, and mitered edges

•  Ground edges are hazy with texture. •  Polished edges are smooth and clear.


Glass Fabrication Miscellaneous Fabrication

•  Drilling, Notching, V-Grooving, and Counter-sinking, etc. –  Any fabrication that affects the

surface or the edge of the glass must be performed before heat-treatment.

–  Strict rules must be followed when drilling, notching or countersinking glass.

•  Hole size •  Distance from edge •  Distance from hole to hole •  Corner and fillet curvature

–  As specified in ASTM C 1048


Glass Fabrication Glass Washing •  Proper glass washing is the most important step in any glass fabrication

process. –  Coating –  Tempering –  Insulating –  Laminating –  Frit Application

•  If glass is not properly washed, none of the above processes will yield successful results.


Automated Glass Washing

•  Glass washing occurs prior to virtually all secondary fabrication processes, e.g. heat-treatment, lamination, spandrel and ceramic frit coating, insulating glass unit fabrication, etc.

•  Proper setup and maintenance of automated glass washing systems is critical to successful glass fabrication and it is one of the fundamental building blocks in the quality assurance process.

•  Water is the foundation of the washer system. Used at high pressure and appropriate temperature, it physically removes particulates. Because water plays many important roles in the cleaning system, water quality is critical.



Click to launch vertical glass washer

Click to launch horizontal glass washer



•  Optimum washer performance requires proper glass loading. Glass spacing should be greater than the roll circumference.

•  Conveyer speeds should provide suitable washer dwell time, and conveyors should not be stopped while glass is under the brushes or air knives.

•  When production rejects occur, an effort should be made to examine glass that has passed through the line washer, but has not yet experienced further processing.

•  Always refer to the machine’s manufacturer troubleshooting guide for reference prior to making any repairs.


Special Precautions For Washing Coated Glass •  The following recommendations are offered to aid in the successful washing

of MSVD coated glass. While all manufacturer recommendations are important, the following are considered critical. And, of course, implementing these recommendations will also improve the efficiency and quality involved with all glass products.

–  Install brushes that have a bristle diameter between 0.006” and 0.009”. –  Keep washer brushes clean and free of grit and abrasives. –  Never allow glass to be stopped in a fixed position beneath the washer brushes. –  All brushes must have sufficient water flow in order to prevent the brush from

scratching the coating. –  Keep pinch rolls clean and free of debris such as process labels. –  Do not allow washer components, such as splash curtains, to drag on the coated

surface. –  The total dissolved solids in the final rinse water must be 20ppm or less. –  Implement a regular and comprehensive preventive maintenance program for the

washer.


Glass Fabrication Glass Surface Compression Annealed Glass

•  Annealed Glass is what comes off the float line. •  Lowest strength form of glass •  Breaks in randomly sized sharp shards •  Used in most Residential and non-critical

applications. •  Used in Commercial applications that don’t

require heat-treated glass for safety or code requirements


Glass Surface Compression Types of Heat-Treated Glass

•  Heat-Strengthened –  About twice as strong as annealed

glass. –  Same chemical resistance and

hardness as annealed glass. –  Breaks into large pieces. –  Used in applications when the glass must

be stronger than annealed, but also increases the likelihood that glass will remain in the frame after breakage

–  Does not meet ANSI Z97.1 or 16CFR 1201 safety glazing requirements

•  Tempered –  About four times stronger than

annealed glass –  Same chemical resistance and

hardness as annealed glass –  When broken, tempered glass

shatters into relatively small pieces (dicing), reducing the likelihood of serious injury

–  Laminated glass may substitute in safety applications

–  Meets ANSI Z97.1 or 16CFR 1201 Safety glazing requirements


Why is Glass Heat Treated?

•  All float glass is annealed—or cooled slowly—after manufacturing to slowly remove residual stresses and make the glass stronger. However, many architectural applications require additional glass strength to withstand both mechanical stresses (such as high wind loads) or thermal stresses (including heat build-up between lites in a window unit).

•  The theory behind heat-treating glass is simple. All glass will break when placed under stress. By creating a condition of stress within the glass itself, an external thermal or mechanical force will have to overcome a higher stress level in order to break the glass—reducing the risk for glass breakage.

•  There are two common heat-treating methods used to strengthen glass: –  Heat Strengthening –  Tempering

•  The specific type of heat treatment required is usually dictated by building codes or industry safety standards.


Fabricator Responsibilities

•  In most cases, tinted substrates and reflective coatings will require heat treatment in order to avoid thermal stress breakage.

•  Fabricators must be aware that certain factors (such as large glass sizes, shapes and patterns; thickness of glass; damage to glass during shipping, handling or installation; orientation of the building; exterior shading; overhangs/fins that reduce wind speed; and areas with high daily temperature fluctuations) can increase the probability of thermal breakage.

•  It is the responsibility of the fabricator to identify and understand the application-specific details of the project and the implication of factors like thermal stress, wind load, and building code compliance. If heat treatment is necessary, heat treatable products must be used.


Heat Treatment Fundamentals

•  To obtain the best optics, a uniform heat saturation of the product must be achieved. Uniform heat saturation is often difficult to obtain with standard radiant furnaces.

•  By introducing convection air during heat treatment, through the use of aspirators, the furnace’s energy is distributed in a more uniform manner. In addition, convection air improves a furnace’s efficiency, and in turn increases yields.

•  Other furnace functions such as the ability to control individual heating elements (top-and-bottom or side-to-side) allow the fabricator greater flexibility when developing heat-treatment profiles.

•  Guardian recommends heat strengthening for all heat-treated applications. Exceptions must only be made when safety or building codes specify tempered glass. Lites must be processed so roll wave will appear horizontal to the base dimension of the finished unit whenever possible.

•  Heat-strengthening greatly reduces the possibility of spontaneous breakage, and toughens the glass approximately two times that of annealed glass of equal thickness and configuration.


How is Flat Glass Heat-Treated? •  The process for heat-treating architectural products calls for glass to be cut

to the desired size and shape, edges prepared to the specified condition, and the surfaces to be washed.

•  The glass is then transported through a tempering oven that raises the glass temperature to approximately 1,150° F, followed by rapid cooling (quenching) by blowing air onto all surfaces simultaneously.

•  The cooling process places the surfaces of the glass into a state of high compression and the central core in compensating tension.


Glass Fabrication Heat-Treating Glass General Overview

•  The heat and quench cycle results in: –  External surfaces (20% top and bottom) cool suddenly and contract. –  Interior bulk (60%) of the glass is still hot and expanded. –  External surfaces become compressed and the interior mass of the glass

is placed into a state of tension. –  The glass will release the tension only when the outer compression layer

is penetrated. –  In essence, the glass is “pre-loaded” with stress that must be overcome

before it will break.


Types of Heat-Treated Glass Heat-strengthened glass

•  Heat-strengthened glass has a much lower potential incidence of spontaneous breakage than tempered glass, and may be used where additional glass strength is required but safety glazing is not required.

•  Flat or bent glass that has been heat treated to have a surface compression between 3,500 psi (24 MPa) and 7,500 psi (52 MPa).

Typical Break Pattern


Glass Fabrication Heat-Treating Glass Applications for Heat-Strengthened Glass

•  Locations where resistance to high wind pressure is required •  Areas where glass is partially shaded •  Applications where additional strength is needed to meet non-wind

mechanical loads (i.e. snow) •  Glazings that may exhibit thermal loads caused by certain tinted or coated

glasses •  Widely used in laminated glass for additional strength, such as in overhead

and sloped glazing •  Spandrel in locations where thermal breakage is a concern •  Significantly reduces the chance of spontaneous breakage caused by

nickel-sulfide inclusions •  NOTE: Heat-Strengthened glass is not approved for use in any safety

glazing application


Types of Heat-Treated Glass Fully-tempered glass

•  Fully tempered glass is most commonly used for applications that require safety glazing.

•  Flat or bent glass that has been heat-treated to have either a minimum surface compression of 10,000 psi (69 MPa) or an edge compression not less than 9,700 psi (67 MPa)



Other Glass Strengthening Techniques Chemically strengthened glass •  Used particularly to strengthen thin glass, involves an ion-exchange reaction which

replaces sodium ions at the surface with bigger potassium ions, putting the surfaces in compression.

•  The stress distribution through the glass is much sharper than for thermal strengthening, with a relatively shallow compression zone and a lower, flatter tensile stress in the core.

•  The chemical strengthening process can be done in approximately 16 hours in a bath of molten potassium nitrate at about 450°C. At the completion of the cycle the glass is air-cooled and washed to remove excess salt.

•  Because chemically strengthened glass breaks in a pattern similar to annealed glass, it is not used by itself as a safety glazing material. It can be laminated for a variety of architectural, security, and transportation applications.



Glass Fabrication Furnace Comparisons

System Radiant Furnace Radiant with Convection

(cold air)

Radiant with convection

(hot air) True Convection

Construction Electric heating

elements

Electric heating elements +Compressed air pipes

blowing cold or preheated air into the furnace, move air -> adds convective heating

Electric heating elements + Piping for

blowing hot turbocharged air into the

furnace, move air -> adds convective heating

Encapsulated heating elements & blowers

circulating hot air in the furnace (electric or gas)

Heating Source

Direct radiation Natural convection

Conduction

Direct radiation Forced convection

Conduction


Conduction


Conduction

Schematic

Presentation

Manufacturers

Glasstech, Tamglass HTF Uniglass, HHH,

TCME

Tamglass Pro E, Tamglass Super E,

Glasstech, Uniglass, HHH, TCME

Uniglass (UniCharge), Tamglass Pro

Convection, Tamglass Super Convection,

Tamglass Sonic, TCME

Glassrobots, Glasstech,

Ianua (ceased operations)


Heating by Convection •  Heating by blowing hot air onto the glass surface

–  Most effective means of heating glass –  In the case of low-e and coated glass, the heat exchange rate is close to that of

clear glasses –  Incorporates aspiration systems or hot fans –  Convection air heated by gas or electricity

•  This method enables high heat-transfer coefficients and improves both process speed and glass quality, especially on high performance coated glasses

Aspiration Convection


Clear / Colored Glasses

Heating rate a function of the thermal conductivity of the glass

Low-E Glasses

Heating rate a function of the thermal conductivity of the glass.

High reflection of indirect radiation

Heating by Convection

Absorption Absorption

Reflected Radiation Convective Heat Convective Heat


Heating by Radiation

•  Heating with electro-magnetic waves from the furnace heating elements –  In recent times, the most common heating source in glass tempering

furnaces –  Heating elements are usually made of resistance heating wire

•  Indirect radiation from heat stored in the furnace structure and fused silica rolls

Radiation Heating



High Absorption depending on glass chemical composition

Low-E Glasses

High Reflection depending on emissivity of coating

Heating by Radiation

IR Radiation Reflected Radiation IR Radiation Reflected Radiation

Transmitted Radiation Transmitted Radiation



Heating by Conduction

•  Heating by direct contact with a hot material –  In modern furnaces, this heating occurs during contact with the furnace

ceramic rolls –  This heating component is quite small compared to radiation and

convection



High Absorption depending on glass chemical composition

Low-E Glasses

High Reflection depending on emissivity of coating

Heating by Conduction

IR Radiation Reflected Radiation IR Radiation Reflected Radiation

Transmitted Radiation Transmitted Radiation



Glass Fabrication Heat Treatment Verification

•  Heat-Strengthened –  Guardian certification requires use

of a Grazing Angle Surface Polarimeter (G.A.S.P.) or equivalent

–  Specification must be within ASTM C 1048 range of 3,500 PSI to 7,500 PSI surface compression

•  Tempered –  Guardian certification requires use

of G.A.S.P. or break test method as specified in ASTM guidelines.

–  Specification: greater than 10,000 PSI surface compression.

G.A.S.P.

ASTM C-1048-04 and ANSI Z97.1 cover the complete

requirements and guidelines when heat-treating flat

glass.


Glass Fabrication Tempered Glass Break Test Verification

•  After tempering, test samples are clamped tightly in a vertical frame –  34” x 76” sample size –  A hundred pound bag of lead shot is

suspended and dropped from: •  12”, 18”, and/or 48” above midpoint

of glass depending on standard

–  If the glass does not break during these tests, it passes

–  If the glass breaks, the ten largest fragments are collected within a 5 minute period.

•  Samples are weighed and compared to the standard according to thickness.


Glass Fabrication Nickel Sulfide Inclusions

•  All float glass contains some level of imperfection. Nickel sulfide (NiS) inclusions are one type of imperfection. Minute nickel particulates from contaminants combine with sulfur from the furnace fuel or batch materials to form nickel sulfide inclusions.

•  Most modern day glass manufacturers have instituted measures to minimize the introduction of nickel (Ni) into the float process.

–  These measures include strict raw materials specifications and handling instructions, clean cullet campaigns, and various process controls.

–  While these procedures have greatly decreased the chance of NiS inclusions leading to spontaneous breakage, the possibility cannot be completely eliminated.

Scanning Electron Microscope (SEM) of a typical NiS inclusion measuring approximately 0.2mm in diameter..

Typical failure pattern of glass following spontaneous breakage of tempered glass containing NiS inclusion


Glass Fabrication Nickel Sulfide Inclusions

•  All float glass contains some level of imperfection. Nickel sulfide (NiS) inclusions are one type of imperfection. Minute nickel particulates from contaminants combine with sulfur from the furnace fuel or batch materials to form nickel sulfide inclusions.

–  In annealed glass, these tiny (less than 1/64-inch diameter) stone-like inclusions are typically harmless.

–  There is, however, the potential for NiS inclusions that may cause spontaneous breakage in fully tempered glass without any load or thermal stress being applied.

–  During the temper quench process (under 650°F), inclusions expand irreversibly (up to 4%) and may produce enough stress to cause spontaneous breakage.


Glass Fabrication Heat Soak Testing

•  Heat soak testing is a process that exposes critical NiS inclusions in fully tempered glass.

–  Europe heat soaks virtually 100% of commercial tempered glass. –  Done in the U.S. as an extra process (if specified) at an additional charge. –  Currently no U.S. standard for heat soaking. Usually done according to E.U.

standard.

•  During tempering the nickel sulfide is transformed to the high temperature α-phase (T>380°C) and has no time to return to the β-phase on quenching. With the passage of time NiS slowly inverts to the low temperature β-phase with an increase in volume of about 4%. This volume expansion may cause glass breakage.

•  During the heat soak process, transformation from α to β-NiS with 99.9 % confidence is less than 1 hour at 280 °C.


Glass Fabrication Heat Soaking

•  Heat soaking is a potentially destructive test. –  Standard heat soak testing requires more than ten hours of thermal treatment

including 1 to 6 hours to heat large quantities of glass up to 290°C followed by a temperature plateau at these temperatures for 3 to 12 hours before cooling down slowly to ambient temperature.

–  This causes glass containing nickel sulfide inclusions to break in the heat soak chamber, thus reducing the risk of potential field breakage.

•  Glass without detrimental inclusions will retain proper temper properties and will have minimal risk of spontaneous breakage in the field.

•  The heat soak process is not 100% effective, but provides a defined level of confidence.


Caution: Fabrication of Post-Heat Treated Glass

•  Fabricating glass after it has been heat-treated by cutting to size and shape, grinding edges, drilling holes cutting notches, grooving, sandblasting and etching may compromise the compression and tension zones of the glass resulting in a weaker or broken piece of glass.

–  Compromising the surface compression zones of fully tempered glass may also negatively affect its ability to comply with the industry safety glazing standards

•  Penetration of a surface compression layer is a major cause of heat-strengthened and fully tempered glass breakage. Since each compression layer in a lite of heat-treated glass is only approximately 20% of the glass thickness, penetration can occur in as little as 0.025” for 1/8” (3 mm) thick glass and 0.040” (1.02 mm) for 1/4” (6 mm) thick glass.

•  Heat-treated glass can be further fabricated by any process that does not alter the surface compression layer such as sputtered (vacuum deposition) coatings onto the surface; assembly of laminates and insulating glass units; and adding films and coatings for opacification.

•  GANA recommends that any fabrication that affects the surface compression layer of heat-treated glass (cutting, edgework, drilled holes, notches, grooving, sandblasting, etching, etc.) be completed before the glass is heat-treated.


•  ASTM C1048 - This specification covers heat-treated flat glass - kind HS, kind FT coated and uncoated glass used in general building construction.

–  Glass furnished under this specification shall be of the following conditions: condition A - uncoated surfaces, condition B - spandrel glass, one surface ceramic coated, and condition C - other coated glass.

–  Flat glass furnished under this specification shall be of the following kinds: kind HS - heat-strengthened glass shall be flat glass, either transparent or patterned, in accordance with the applicable requirements, and kind FT - fully tempered glass shall be flat glass, either transparent or patterned in accordance with the applicable requirements.

–  All fabrication, such as cutting to overall dimensions, edgework, drilled holes, notching, grinding, sandblasting, and etching, shall be performed before strengthening or tempering and shall be as specified.

–  Requirements for fittings and hardware shall be as specified. In heat-strengthened and fully tempered glass, a strain pattern, which is not normally visible, may become visible under certain light conditions.

–  The support system and the amount of glass deflection for a given set of wind-load conditions must be considered for design purposes.

–  Heat-treated flat glass cannot be cut after tempering. Heat-treated glass can be furnished with holes, notches, cutouts, and bevels.

–  The expansion fit and porosity of the ceramic coating shall be tested to meet the requirements prescribed. Specimens for evaluation of resistance to alkali and acid shall be prepared and tested to meet the requirements prescribed.

Caution: Fabrication of Post-Heat Treated Glass


Heat Soak Testing Standards

•  Heat soaking is an offline process that is performed by placing glass that has been cut, edge seamed and thermally tempered into an oven that has been specially designed for the heat soak process.

•  There is no established standard for heat soaking in the United States, Canada, or Mexico. The European Union has established EN 14179-1 “Glass in Buildings – Heat Soaked Thermally Toughened Soda Lime Silicate Safety Glass,” which is the European standard for the heat soak process. This standard defines both the heat soak process/procedure and the heat soak oven calibration procedure. It also lists the residual risk of spontaneous breakage as “one breakage in 400 tons of heat soaked thermally toughened soda lime silicate safety glass.” If project managers conclude that heat soaking is appropriate, Guardian SunGuard heat treatable coated glass products may be heat soaked in accordance with this standard.

•  Heat soaking may not be 100% effective in eliminating spontaneous breakage due to NiS inclusions. Further, heat soaking carries a slight risk of reducing the surface compression of tempered glass during the process. For this reason, Guardian recommends checking surface compression of randomly selected lites prior to heat soaking and after the process is completed.


Heat Soak Testing Standards

•  Precautionary Measures –  As with any offline process, heat soaking carries with it certain risks

associated with the additional handling of the glass. This includes scratching, abrasion, chipping and breakage. Excerpts from the Fabricator User’s Guide are provided below for proper handling of coated glass products.

–  In addition, Guardian recommends that thermocouple leads should not be attached to coated glass surfaces, only to uncoated glass surfaces. If breakage occurs in the heat soaking oven, adjacent lites must be closely inspected to ensure scratch-free glass.


Glass Fabrication Spontaneous Breakage

•  Heat-treated glass will break if the compression layer is penetrated. •  Surface or edge damage which does not penetrate the compression

layer may propagate due to thermal or wind cycling. •  Common Causes

–  Surface or edge damage –  Deep scratches or gouges –  Weld splatter –  Missile/windborne debris impact –  Glass to metal contact –  Wind/thermal loading –  Inclusions (nickel sulfide)


Glass Breakage Tempered Glass •  When tempered glass breaks, the energy retained in the glass due to

internal tension/compression releases explosively and produces a breakage pattern sometimes called “cubes’.

•  Seeing a cubist breakage pattern does not tell you why the glass broke, it only tells you that the glass was tempered. Generally, there are three reasons tempered glass will break: impact, edge damage or nickel sulfide inclusions.

•  Normally, when tempered glass breaks, it falls down into a pile of little cubes. Piecing the broken cubes back to together is the most reliable way to determine the cause of breakage. However, occasionally the pieces of broken tempered glass will stay in the opening, locked to each other like blocks in a masonry arch. And just like in a masonry arch, if you remove the keystone, the arch – or glass in this case – comes tumbling down.

•  When a tempered, laminated glass unit is broken, the interlayer holds the pieces in place, making it much easier to understand the origin of the break.


Glass Breakage Impact Breakage •  When glass breaks as a result of impact, the breakage pattern will vary

depending on the speed and mass of the object impacting the glass and glass thickness and post-annealing treatments that were performed on the glass.

•  When an object squarely hits a piece of annealed glass, it will produce a circular puncture with cracks emanating outward from the point of impact.

•  The resulting shards between these cracks are dangerous. Experienced glaziers often tape the shards together with duct tape, then remove the entire panel.

Glass shards from broken annealed or heat strengthened glass are dangerous and must be handled with care.

Typical impact break without puncture


Glass Breakage -Blunt or Distributed Impact and Small Rock, High Velocity •  Blunt or Distributed Impact on Long, Narrow Lite of Annealed Glass

–  In this type of break, there is a horizontal crack at the center of the blunt impact, with cracks radiating away from the impact. Due to the aspect ratio (relationship between width and height), shards are long and narrow.

•  Small Rock High Velocity –  When a small object impacts annealed glass at a high rate of speed, the object

can completely puncture the glass. The combination of size and speed causes a localized pattern of damage.


Glass Breakage Larger Rock, Less Velocity

•  A larger object impacting annealed glass at a lower rate of speed causes a larger area of damage; however, the object is unlikely to completely penetrate the glass.

•  If the impact is large enough, it is possible to break the interior lite of an insulating glass unit. In the picture below you can see two sets of impact breakage patterns.


Glass Breakage Spontaneous Breakage •  Glass, and especially tempered glass, sometimes breaks all by itself. This is

often the result of insufficient or improper treatment of the glass edges prior to installation in the glazing system.

•  Another reason for spontaneous breakage in tempered glass is the rare occurrence of nickel sulfide inclusions. A nickel sulfide inclusion is a tiny rock of unmelted material that remains in the glass. This tiny rock embedded in a slab of glass which is under high tension/compression forces, that can weaken the glass and eventually cause breakage.

•  The inclusions are so tiny that they can be very difficult to see with the unaided eye.


Glass Breakage Stress Cracks •  A “stress crack” will usually only happen in annealed

or heat strengthened glass. Stress cracks emanate from the edge of the glass and propagate throughout the vision area.

•  If annealed glass is subjected to thermal fluctuations beyond its capabilities, it will break in a way that will relieve the stresses induced by the thermal changes.

•  This type of break has a nearly identical pattern to spontaneous breakage that is associated with glass edge damage.

•  To tell the difference between a true stress crack and a crack due to edge damage, look at the edge of the glass for a chip.

•  Another clue would be the distribution of glass breakage in the building. It would be normal to find stress-like cracks on elevations with greater temperature swings. But does the breakage also coincide with the use of reflective interior blinds, especially in a partially opened position? That would be indicative of a true stress crack, rather than a crack induced by edge damage.


Glass Breakage •  Thermal Breakage

–  Thermal stress is caused when the central area of the glass is heated (naturally or artificially) and expands, while the glass edges remain cool resisting expansion.

–  Thermal breakage is the result of an excessive build-up of thermal stress in annealed glass. The amount of thermal stress depends upon the temperature difference between the hottest and coldest areas of the glass and also on the distribution of the temperature gradient across the glass.


Glass Breakage

•  Thermal Breakage –  Glass which has cracked as a result of thermal stress can be easily

identified by the break pattern which is unique to a thermal fracture. –  The crack in the glass is initially at 90° to the edge and glass face for

approximately 2-5cm and then branches out into one or more directions –  The number of branches or secondary cracks in dependent on the

amount of stress in the glass.


Glass Breakage

•  Factors affecting thermal stress –  Geography, climate and site plan –  Glass type, size and thickness –  Glass edge condition –  Glass construction and glazing system design –  Internal and external shading –  Internal HVAC

•  When thermal breakage is a concern, heat-treated glass should be specified as it has higher compressive stresses which resist thermal breakage.

Glass TypeSolar

AbsorptionRisk of Thermal

Breakage

Clear 18% Low

Standard Tint 30-40% Medium

Dark Tint 45-65% Medium - High

Reflective coating on clear substrate 60-70% High

Reflective coating on tint substrate 80-85% Very High

Risk of Thermal Breakage


Guideline for Use of Heat-Treated Glass To Reduce The Likelihood of Thermal Breakage

55

50

45

40

35

30

25

20

15

10

5

0120 125 130 135 140 145 150 155 160 165 170 175 180

Heat treated glass advisedCaution - site specific conditions may require heat-treated glassAnnealed glass is typically sufficient

Glass Thermal-Stress Temperature (˚F)

Max

imum

Gla

ss A

rea

per

Lite

(ft2 )

Heat-Treated Glass Guide Based on Surface Area and Thermal Stress Temperatures


Glass Fabrication Heat Treating Distortion •  Moving glass on heated rollers will

cause some distortion. –  Roll Wave – distortion caused by

ceramic rollers in the furnace –  Bow – curvature up or down from

the horizontal plane –  Warp – a twisted bend or

curvature. –  Strain pattern (iridescence)

•  Especially visible in reflective applications

•  See ASTM C 1048 for additional information.

•  Inspection methods are necessary.

–  Zebra board –  Roll wave gauge


Glass Fabrication Roll Wave •  Lites must be processed so roll wave will be horizontal to the base dimension of the

finished unit, whenever possible. •  A Roll Distortion Gauge is used to measure roll distortion (See below)

–  The gauge is passed over the uncoated surface or bottom side of the glass in both the x and y dimensions.

–  The gauge takes peak to valley measurements. Extremes in roll wave, center and edge kink will be determined during this measurement.

•  Guardian requires a target of 0.07mm (0.003 in.) with a maximum of 0.13mm (0.005 in.) roll wave for any commercial application. The intent is that 99.9% of the glass supplied is less than or equal to 0.07mm (0.003 in.). Fabricators are required to develop improved in-house specifications for maximum roll wave. These specifications should be based on both furnace capabilities and aesthetic expectation for the product.


Glass Fabrication Inspection Methods & Devices

Zebra Board and Inspection Table Light Board (In Transmission)

Roll Wave Gauge Light Board (In Reflection)

10 feet

10 feet


Glass Fabrication Central Viewing Area

•  The area of most importance during visual inspection is the Central Viewing Area. –  The Central Viewing Area is defined by 80% of the length and 80% of

the width dimensions centered on a lite of glass. –  The remaining area is considered the outer area.

•  An example of the central viewing area of a lite that is 2540mm by 1016mm (100 in. x 40 in.) is shown below.


Heating Principle (Radiant vs. Convection furnace)

Radiant Furnace Convection Furnace Direct Radiation

Indirect Radiation

Natural Convection

Forced Convection

Conduction

Glass Fabrication Types of Heat-Treating Furnaces


Optical Distortion •  Many conditions may contribute to optical

distortion, including glazing errors and processing procedures.

•  Minimizing optical distortion resulting from a heat treatment process will greatly enhance the appearance of the final product.

•  Roller wave and bow are sources of optical distortion that can result from tempering or heat strengthening and as such influence the appearance of the final product.

–  Roller wave occurs as glass passes over the rollers in a horizontal, oscillating heat treatment furnace.

•  As the glass heats up, it may sag between the rollers at the reversal of each oscillation, which then becomes "set" in place during the cooling (quench) process. This may produce roller wave distortion in the finished product.

•  Lites must be processed so that roll wave will be horizontal to the base dimension of the finished unit, whenever possible.

–  Bow occurs as a result of the heat treatment process and can be reduced through the correct control of the heating and cooling process


Strain Pattern

•  Strain pattern refers to a specific geometric pattern of iridescence or darkish shadows that may appear under certain lighting conditions, particularly in the presence of polarized light (also referred to as "quench marks", "leopard spots" or anisotropy).

•  The phenomena are caused by the localized stresses imparted by the rapid air cooling of the heat treatment process. Strain pattern is characteristic of heat treated glass and is not considered a defect.

Normal View Polarized View


Strain Pattern

Normal View Polarized View


Current Standards Technical Organizations and Associations

•  GANA [Glass Association of North America] –  Maintains Engineering standards manual –  Has no standard for distortion (roll wave) –  Has standard for Bow and Warp –  Follows ASTM and ANSI Standards

•  ASTM [American Society for Testing and Materials] –  C 1048 – Heat-Treated Flat Glass –  Has no standard for distortion (roll wave) –  Has standard for Bow and Warp

•  ANSI [American National Standards Institute] –  Z-97.1-1984 Safety Glazing Materials –  Specific requirements for safety glass –  Places specifications on tempered glass particle size –  No standard for distortion (roll wave)

•  16 CFR 1201[Code of Federal Regulations]


Kinds of Distortions Found in Flat Glass

•  Roll Wave - Roller Wave •  Bow - Warp, Oilcan •  Cord - Ream, Knot, Cat Scratch

•  Pocket - Bird’s Eye, Hammer •  Edge Kink •  Center Kink •  Picture Frame •  Mechanically Induced (Frame/

Gasket Impingement)


Roll Wave

•  Roll wave is the deformation of horizontal heat-treated glass that occurs when the softened glass passes over the conveyor rollers.

•  The effects of roll waves in architectural glass are most apparent when reflected images appear distorted, as in a “fun-house” mirror.

•  Glass with minimal roller wave distortion is typically regarded as a sign of premium product quality. –  Complete elimination of roller wave is

unavoidable.


Quantifying Roll Wave Optical Distortion

•  Zebra boards –  Subjective assessment –  Provides quick check of Heat-Treat Process

conditions –  Product should not be rejected based on

subjective analysis.

•  Roll Gauge –  Quantitative measurement of roll wave –  Real time feedback instrument –  Standards determined by manufacturer and

industry practice –  Same techniques used on all furnaces


Zebra Board - Subjective Evaluation of Roller Wave •  Fabricators have historically relied on so-called

Zebra boards to detect any major flatness defect as the lites of flat glass emerge from the tempering furnace.

•  A “Zebra” board is often mounted at the exit of a tempering furnace or at an off-line inspection table. The operator looks at the reflection of the lines in the glass and notes any significant flatness defect as unacceptable rollerwave distortion.

•  At best, Zebra boards are only capable of providing a subjective evaluation of the degree of roll wave distortion present in the glass.

•  Over-reliance on subjective measurement techniques such as the Zebra board raises the likelihood that glass will slip through that is out of specification for roller-wave, and the problem may be compounded by inconsistency from batch to batch – and even lite to lite.

•  The only thing worse than bad roller wave is different roller wave between adjacent lites. The inconsistency tends to magnify the undesirable distortion effect.

Progressive Roll Wave Distortion


Handheld Roller Wave Gauge – Objective Evaluation of Roller Wave

•  The optical quality of heat treated glass can also be quantatively measured by using a roller wave gauge. Roller wave gauges are designed for off-line inspection of heat strengthened or fully tempered glass.

•  A roller wave gauge traces the glass surface measuring the maximum “peak-to-valley” depth and length of the roller wave so that the optical distortion can be calculated (a conversion chart is supplied with the instrument).

•  The peak-to-valley depth and wavelength values are usually stated in inches or millimeters, while the optical distortion is expressed in millidiopters (mdpt).

•  The length of the roller wave usually corresponds to the circumference of the conveyor rollers. Measurements should not be taken closer than 6” from the edge to eliminate normal edge kink.



•  Cord – also described as Ream, Knot or Cat Scratch –  A type of optical distortion caused by localized glassy inclusions with a different

chemical composition than that of the surrounding glass, usually caused when glass layers are folded when stirred in the melting chamber or by non-uniform heating.



•  Bow – also described as Warp, Oil can, Saddle Bow or Bi-stable Bow –  An overall curvature of the glass (concave or convex) due to an imbalance of top

and bottom surface stresses, caused by non-uniform cooling in the tempering quench cycle.


Normal Reflected Image

Swirled (Distorted) Image


•  Concave Distortion (Bow) Caused by Mechanical Means –  The distortion of the reflected tree in the lower IG unit is due to distortion in the

outboard lite caused by horizontal stacking prior to sealing. This unit was on the bottom of the assembled unit table stack without proper support.



•  Pocket – also described as Bird’s Eye or Hammer –  Localized angular deformations caused by worn or damaged rollers, non-uniform

heating or cooling, or buildup of SO2



•  Roll Wave or Roller Wave –  A repetitive wave-like departure from flatness that

occurs in otherwise flat, heat-treated glass as it moves across ceramic rollers in a horizontal roller hearth furnace.

–  Good roller bed maintenance and uniform heating and cooling can minimize roll wave distortion. Some experts recommend running the glass as cool as possible, while closely monitoring surface stress levels to assure fragmentation and load-strength requirements are being met.


Leading Edge Kink

Trailing Edge Kink

Kinds of Distortions Found in Flat Glass •  Edge Kink

–  Edge kink is a deviation from flatness (up or down) at the unsupported leading or trailing edge of a heat-treated glass lite, primarily due to the separation/space between the exit of the oven and the first quench roll and the position of the first quench nozzles in relationship to the spacing and the first quench roll.

–  It may be minimized by positioning lites at an oblique angle on the conveyor. –  In addition to distortion, excessive edge kink in glass used for IG or

laminated units can result in delamination and field failures.



•  Center Kink –  Center kink distortion is most noticeable and prevalent on soft-coated glass that

was not heated properly or long enough to allow the glass to lay completely flat on the furnace rollers. When glass first enters a heat-treating furnace, it may bow up along the edges. With inadequate heating of the top surface of the glass, the center never becomes soft enough to allow the lite to flatten out.



•  Picture Frame –  Normally seen on coated glass, extending approximately ½” -1” in from the edge

around the perimeter of the glass.



•  Mechanically Induced (Frame/Gasket Impingement)


Glass Fabrication Overview •  To provide information on spandrel, screen printing, laminating, insulating

and glazing. –  Develop awareness of laminated glass codes. –  Describe the insulating process, including key components –  To understand the differences between standard and warm-edge spacers –  To provide a general overview of glazing


Glass Fabrication Spandrel Applications •  Used in glazing applications that need to be

opaque. –  Hung-ceiling areas –  Knee-walls –  Columns

•  Mechanical equipment areas •  Various types of spandrel

–  Ceramic frit –  Silicone paint –  Polyester film –  Shadow-box

•  Due to potential thermal breakage, all spandrel glass should be heat-treated.

IG

IG

Insulation

Spandrel

Air space


Glass Fabrication -Screen Printing •  Used to decorate glass with colors.

–  Aesthetics − Privacy –  Solar Control − Advertisements –  Spandrel − Lighting Applications –  Labels

•  Screen is made of porous fabric and mounted to a frame.

–  Image is transferred to the fabric and surrounding area treated with a chemical to fill in the holes.

•  Screen mounted to print machine and paint or frit is poured onto the screen and squeezed through the holes under uniform pressure.

•  Before heat treating, ceramic frit must be fully cured

•  When the frit is heat-treated, it bonds strongly to the surface.

•  Common patterns are dots, stripes, or holes.


Glass Fabrication Laminated Glass

•  Typical uses –  Safety –  Security – Blast and bullet resistance –  Noise abatement –  Fallout resistance – hurricanes –  Solar control (tinted pvb or coatings) –  UV Blocking –  Structure

•  Automotive front windshields •  Overhead and sloped glazing •  Burglar/Bullet/Attack resistant glass •  Glass floors •  Specialty applications


Glass Fabrication Laminating

PVB Interlayer

~HEAT~

* PRESSURE *


Glass Fabrication Laminating

•  Two or more lites of glass and one or more interlayers of polyvinyl butyral (pvb) bonded together under heat and pressure.

•  Other materials may be used in place of pvb •  Resin Laminating

–  Two or more lites bonded with a cured resin interlayer

•  Glass-Clad Polycarbonate –  One or more lites of glass and one or more

sheets of polycarbonate with an aliphatic urethane interlayer between the two, bonded together under heat and pressure.


Glass Fabrication Laminated GlassInterlayers •  Conventional Laminating

–  A polyvinyl butyral (pvb) sheet is sandwiched between two sheets of glass (or polycarbonate), compressed & heated, then autoclaved for about 4 hrs at 240°F with a pressure of 160 psi.

–  Typical interlayer thicknesses – .38mm, .76mm, 1.14mm, 1.52mm –  WHY?.......... Because - .015”, .030”, .060”, .090” or combinations –  Many color options

•  Resin Laminating –  Sheets of glass are assembled with a space maintained between the lites. –  Liquid resin is poured into the cavity, & when cured forms a rigid interlayer.


Glass Fabrication Laminated Glass Manufacturing Process •  Seven Basic Steps:

–  Automatic cutting –  Washing –  Layering –  Preheating –  Autoclaving –  Testing –  Finishing


Glass Fabrication Manufacturing Process Layering •  Manual process:

–  Assembly of the glass/pvb interlayer sandwich takes place in an enclosed area. •  Controlled Temp. •  Controlled Humidity •  pvb is hygroscopic – tacky at room temperatures.

–  Product must be dry & temperatures maintained at ≈40°F until the moment of use.


Glass Fabrication Manufacturing Process Layering


Glass Fabrication Manufacturing Process Pre-Heating •  After layering, the glass sandwich is preheated to ≈140°F. •  It passes through a nip roll that:

–  Removes air –  Heats the material –  Provides pressure and adhesion

•  Enables the glass to be transported as a translucent product ready for the autoclave process.


Glass Fabrication Manufacturing Process Autoclaving •  Preheated laminated sheets are placed into a heated autoclave. •  Sheets are heated to 240°F at 160 psi •  Process takes ≈4 hours

–  Rapid heat-up –  Next, a 15 minute “holding time” to allow the heat to penetrate the glass. –  Cool down cycle brings the temperature back to an ambient state, after which the

air pressure is released.

•  Autoclave heat & pressure –  Converts translucent pvb into a clear adhesive –  Removes/absorbs all the air trapped in the unit.


Glass Fabrication Manufacturing Process Autoclaving


Glass Fabrication Testing

•  Pummel Tests –  Pounding the glass away from the pvb interlayer. –  The resultant fracture pattern is a measure of adhesion.

•  Bag Impact Tests –  Category I

•  100 lb shot bag that is elevated to 18” and swings into the glass to measure material strength.

•  Bag is not to pass through any tears in laminate.

–  Category II •  Same test as Category I utilizing 48” height.

•  Specifications –  ANSI Z97.1 –  16 CFR 1201 Cat I & II


Glass Fabrication Testing •  Ball Drop Test (Automotive)

–  Dropping ½ lb ball onto the glass from 10’ to measure the material strength –  Ball must not pass through the glass –  ANSI Z26.1

•  Environmental Test –  Laminate is boiled in water for 2 hours to test adhesion of pvb to glass


Glass Fabrication Applications •  Hurricane Resistant Glazing - flying projectiles & pressure cycling •  Safety Glass - fallout and lacerations •  Security – vandalism and break-in resistant •  Ballistic Glass - firearms protection •  Blast Resistance – bomb blasts •  Earthquake Resistance – Code in early development •  Noise/Sound Reduction - airports, traffic •  Solar Management - UV control, heat absorption •  Decorative Applications


Glass Fabrication Hurricane Glazing

•  Provide protection from flying/falling debris & aftermath vandalism

•  Standards –  ASTM F 1642 - Standard Test Method

for Glazing & Glazing Systems - Subject to air blast loadings.

–  ASTM E 1886 - Standard Test Method for Performance of Exterior Windows, Curtain Walls, Doors, & Storm Shutters - Impacted by missiles & exposed to cyclic pressure differentials.

•  Dade County, FL has led the way for hurricane standards.


Glass Fabrication Hurricane Glazing •  Building code mandated

compliance in many Atlantic and Gulf Coast areas

•  Meets large & small missile requirements

•  Protects building envelope from windborne debris internal pressurized damage


Glass Fabrication - Laminated Glass Hurricane Glazing Testing •  Large missile testing

–  Simulates flying boards & debris –  Utilize 0.090 or 0.100 gauge pvb interlayer @ bldg. heights less than 30 feet

•  Small missile testing –  Simulates flying roof tiles –  Utilize 0.060 gauge pvb interlayer @ bldg. heights greater than 30 feet

•  After impact testing, glazing system must pass cyclical air, water & structural testing.


Glass Fabrication Hurricane Glazing Large Missile Testing


Glass Fabrication Safety Glazing •  Glass configurations that are designed to help protect building

occupants from injury or loss due to accidental or natural causes. •  Fragments adhere to interlayer & continue to protect building

occupants & components. •  Meets same safety glazing codes as tempered glass. •  Standards

–  Consumer Product Safety Commission (CPSC) Standard 16 CFR Part 1201 – Safety Standard for Architectural Glazing Materials.

–  ANSI Z97.1 – Standard Specification for Safety Glazing Materials used in Buildings Safety Performance Specifications and Methods of Test.


Glass Fabrication Security •  Security Classifications

–  Attack resistance –  Ballistics resistance


Glass Fabrication Security Attack Resistance •  Glass configurations that are designed to help protect

building occupants from injury or loss due to deliberate or intentional actions.

•  Standards –  ASTM F-1233 – Standard Test Method for Security

Glazing Materials and Systems. –  UL 972 – Standard for Safety for Burglary Resisting

Glazing Material.


Glass Fabrication Security Ballistic Resistance •  Resists ballistic attacks in appropriate configurations

based on predictions. •  Typically glass-clad polycarbonate combinations •  Standards & Ratings

–  ASTM F-1233 – Standard Test Method for Security Glazing Materials and Systems.

–  UL Standard 752 – Standard for Bullet Resisting Equipment

–  NIJ Standard 0108.01 – Standard for Ballistic Resistant Protective Materials


Glass Fabrication Blast Resistance •  Protect people inside or near a building subjected to air blast pressure

loading.


Glass Fabrication Blast Resistance •  Ideally, glazing materials will remain in framing following fracture,

eliminating flying & falling glass shards & their associated hazards.


Glass Fabrication Blast Resistance •  Basic Recommendations

–  Laminated glass fabricated with minimum 60 gauge (.060") interlayer thickness.

–  Use of annealed or heat-strengthened glass is preferred as they produce larger shards upon fracture & adhere well to the pvb interlayer.

•  Standards & Ratings –  ASTM F 1642 - Standard Test Method for

Glazing & Glazing Systems - Subject to air blast loadings.

–  GSA -General Service Administration level C & D Specifications.

–  ISC - Interservice Security Council. –  Dept. of Defense anti-terrorism

specifications.


Glass Fabrication Noise Reduction & Solar Management

•  Laminated glass products can reduce perceived noise by nearly 50% over monolithic glass.

•  Standard –  ASTM E 1332 – Standard Classification for

Determination of Outdoor-Indoor Transmission Class

–  ASTM E 1425 - Standard Practice for Determining the Acoustical Performance of Exterior Windows and Doors

•  Blocks out >99% of UV light –  Untreated glass blocks <15% UV. –  Average low-E coatings block <70% UV.


Glass Fabrication Insulating Glass •  Two or more lites of glass

hermetically sealed together. (Insulating Glass or IG).

•  Reduces heat gain/loss through the window.

•  Spacers are used around the perimeter.

•  Sealants used to hold the glass and spacers together.

•  Inert gases may be injected into the sealed unit air space to enhance insulating performance.


Glass Fabrication Insulating Glass •  Found in 95% of all new residential windows. •  87% of all commercial applications. •  Improves energy efficiency. •  Reduces sound transmission as compared to single pane glass. •  All Guardian sputtered coatings sold in North America must be placed within

insulating glass units.


Clear Double Insulating Glass Spectral Diagram


Clear Triple Insulating Glass Spectral Diagram


Glass Fabrication Insulating Glass Components •  Glass •  Spacer •  Desiccant •  Gas Fill •  Primary Seal •  Secondary Seal Inert Gas (Ar,

Kr, Xe, etc.)

Spacer & Desiccant

Secondary Seal

Primary Seal

Glass


Glass Fabrication Insulating Glass (IG) Spacers •  Types

–  Conventional –  Warm-Edge

•  Creates the airspace between two or more lites of glass. –  The airspace provides significantly improved insulation properties as compared

to single lites of glass.

•  Holds desiccant to keep airspace dry •  Spacers and corner connectors create a system that supports and

enhances the sealing of the IG unit. •  Solid moisture barrier


Insulating Glass (IG) Spacers Conventional •  Conventional

–  Usually made of aluminum or steel that is roll-formed –  High thermal conductivity at the perimeter results in decreased performance of

the entire glazing. –  Relatively inexpensive and commonplace –  Sealants have been proven over time to work well with steel and aluminum. –  Desiccant is usually placed into the roll formed tube in pellet form.


Insulating Glass (IG) Spacers – Warm Edge •  Variety of competing technologies.

•  Metal •  Plastic •  Foam •  Combinations

–  Decreasing the thermal conductivity of the spacer while improving the performance of the overall window.

•  Warm edge is dominant in the residential market.


Glass Fabrication Insulating Glass (IG)Desiccants •  Defined as a substance having a great affinity for water and

used as a drying agent. –  Usually silica gel or Zeolite molecular sieve or a blend.

•  In IG’s, a substance that is capable of removing water from the inside of an IG unit that works at low humidity.

•  For conventional IG, found around the perimeter, usually within the spacer in the form of loose-filled beads.

•  Warm edge is supplied in a hot or cold applied desiccated matrix (tape, gel or gum-like) form. Functions

–  Water vapor condensing on the inner glass surfaces of an IG unit will produce visible fog. Desiccants remove this water vapor.

–  Solvent vapors can condense on the inner glass surfaces of an IG unit producing a chemical fog. Desiccants remove this vapor.


Glass Fabrication Insulating Glass (IG) Gases •  Insulating Gases

–  Air (dry) •  Most common

–  Argon •  High performance residential •  Not common in commercial

–  Krypton (rare) –  Xenon (very rare) –  Sulfur Hexafluoride

•  Sound Dampening •  Changes the speed of sound (refracts the sound waves.)

•  Differences in performance are due to the differing thermal conductivity of the gases.

•  Gas retention is a critical issue in regard to insulating glass units.


Glass Fabrication Insulating Glass (IG) Gases

U-Value based on Fill Gas and Gap WidthSN-68 on #2 on 6mm with Clear Inboard

0.2

0.22

0.24

0.26

0.28

0.3

0.32

0.34

0.36

0.38

0.4

0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

Gap Width (in.)

U-Va

lue

AirArgonKrypton


Glass Fabrication Insulating Glass (IG) Sealants •  Primary Seal

–  Almost always Polyisobutylene (PIB) •  Good gas retention properties •  Good MVTR (moisture vapor transmission rate)

•  Secondary Seal –  Hot-Melt Butyl –  Polysulfide –  Polyurethane –  Silicone

•  Warm-Edge Sealant Spacer Combinations –  Swiggle Seal –  Duralite/Duraseal –  Intercept –  Super Spacer –  Technoform

Inert Gas (Ar, Kr, Xe, etc.)

Spacer & Desiccant

Secondary Seal

Primary Seal

Glass


Glass Fabrication Insulating Glass (IG)Sealants •  Attributes

–  Must have good adhesion to glass and spacer –  Must have good weatherability

•  Water exposure (Low MVTR) •  UV Light exposure •  Temperature extremes

–  Must be applied easily and quickly. –  Must be inexpensive –  Must be compatible with the type of glazing


Glass Fabrication Insulating Glass (IG) Sealant Application •  Pump (hot or ambient) •  Extrude (semi-auto or auto) •  Trowel (hand mix and apply with trowel) •  Hand Apply (bead or rope form)


Glass Fabrication Edge-Deletion •  The removal of coating around the

perimeter of the glass. –  Grinding wheel is used. –  Can be automated. –  Usually between 3/8”-1” strip around

the edge. •  Edge-deletion may be required for

low-E coatings in IG Units. –  Chemicals in the sealants may react

with the coating. –  Black edge corrosion (from the silver

in the coating) is not aesthetically pleasing.

–  Reflected coating color may shift after insulating.


Glass Fabrication Muntin Bars

•  Aesthetic decoration to simulate divided lite glazing

•  More efficient and less expensive than true divided lites.

•  Several types –  Historical muntin bars –  Simulated divided light –  Between-the-glass muntin bars –  Grilles between-the-glass –  Removable interior muntin bars


Glass Fabrication Bending •  Glass is heated to between

1000°F and 1100°F. •  Through gravity (sag method)

or mechanical means (press method), the shape is formed and allowed to cool.

•  Sharp angles and compound curves are common.

•  Glass can be annealed, heat-strengthened or fully tempered. Coated or non-coated.


Glass Fabrication Types of Bending •  Convex bend

–  Bend into a mold

•  Concave bend –  Bend on top of a mold

•  Coated glass can be bent with certain precautions.


Glass Fabrication Bending Terminology

•  A great deal of information is required when considering bent applications.

•  Please consult Guardian literature (Bending Product Application Note) for details on bending.

•  It is imperative that customers produce a full scale mock-up prior to accepting final order.

•  It is advisable to contact STC Customer Engineering for assistance with bent glass applications.


X. Commercial Wall and Glazing System Design


Glass Fabrication Glazing •  The process of placing glass into a prepared opening. •  Types of Glazing

–  Wet - securing glass in a frame that uses sealants or glazing compounds –  Dry - securing glass in a frame using preformed, resilient elastomeric gaskets –  Pressure – pressure used to achieve weather tightness –  Butt-joint – monolithic lites are glazed together at the edge –  Structural Silicone– silicone is used as a structural support for a lite or IG unit.

Two or four sided is possible –  Sloped – glazing at more than a 15° angle from vertical


Punched Opening Wall Systems

•  Punched opening windows get their name based on the concept that a cookie-cutter type hole is punched in the exterior wall of the building and filled with a window.

•  Framing can be fabricated from minimal depth aluminum framing members, or may be of the same sized members used to construct a curtain wall frame depending on size and specified performance criteria.

•  Can be designed as pre-glazed or “open” for field glazing


Window Wall Systems

•  A window wall is a term that can be used to describe various applications of glazing systems that install between floor slabs.

•  This term can be used for ribbon windows, storefronts, or other glazed openings that form a wall of glass in a single story application.

•  A window wall system can be fabricated from heavy aluminum framing members or light weight, shallow depth members depending on design criteria.


Ribbon Window Wall Systems

•  Ribbon windows get their name because they simulate the look of a ribbon wrapped horizontally around a gift box.

•  Ribbon window systems are popular in office building construction and can be any height between typical floor slabs. They are usually installed between spandrel panels of stone, aluminum, or concrete.

•  Ribbon windows are typically cost-effective, so long as opening heights are modest and modules are kept repetitive.

•  These types of systems can be designed to install in a variety of ways including shop-glazed (unitized) or field-glazed (stick-built).


Structural Glass Wall Systems

•  Structural glass walls are typically frameless with support provided by unique ways of retaining high-span glazing applications without the use of conventional aluminum framing members or structural floor slabs to anchor back to.


Curtain Wall Systems

•  A curtain wall is a wall system that incorporates glass (vision and / or spandrel) and vertical and horizontal mullions acting as structural members to transfer wind and gravity forces to the building structure.

•  The key difference between a curtain wall and a window or window-wall, is that a curtain wall fits outside the building structure while windows fit within an opening.

•  Curtain wall mullions and glass run vertically past the floor slabs. Mullions are anchored back to slab edges.



•  Vision glass is predominantly insulating glass and may have one or both lites laminated, usually fixed but sometimes glazed into operable window frames that are incorporated into the curtain wall framing.

•  Spandrel glass can be monolithic, laminated, or insulating glass.


Curtain Wall System Types Pressure-Equalized Rain Screen •  Pressure-equalized rain screen

–  These systems function by blocking all of the forces that can drive water across a barrier. As related to curtain wall systems, PE rain screen systems design the inside face of glass and the inside face of the glazing pocket and the interconnecting gasket or wet seal as an airtight barrier.

–  The outside face of glass, exterior glazing materials and the outer exposed face of aluminum framing function as a rain screen, shedding water away.

–  Between the exterior rain screen and the interior air barrier a pressure-equalization chamber is formed in the glazing pocket, which serves to reduce water penetration by eliminating (equalizing) the pressure difference across the rain screen that tends to force water into the system. Minor amounts of water that may penetrate the system are wept harmlessly to the exterior.

–  Detailing of spandrels, shadow boxes and interface with adjacent construction must maintain the continuity of the air barrier and rain screen to function properly with a pressure-equalized rain screen curtain wall framing system.

–  Normally, pressure-equalized rain screen systems provide the highest levels of resistance to air and water infiltration.


Curtain Wall System Types Pressure-Equalized Rain Screen •  How a pressure-equalized rain screen

system works –  The curtain wall pressure-equalized rain

screen system incorporates a cavity behind the curtain wall. Vents in the curtain wall equalize the cavity pressure to the outdoor pressure, decreasing the pressure-driven rain penetration into the cavity. These vents must be designed to prevent rain penetration due to gravity, capillary action and kinetic energy. The cavity must be well drained to the outside in order to remove any water that does penetrate.


Curtain Wall System Types

•  Water-managed system –  Weep holes in a water-managed system

function largely to drain water that enters the glazing pocket while weep holes in a pressure-equalized system function primarily as vents to allow air movement between the exterior and glazing pocket. Weeping of water is only a secondary function.

–  The easiest way to recognize a pressure-equalized rain screen system is to note that the glazing pocket around each individual unit of glass is isolated air tight from adjacent units, most obviously with plugs or seals at the gaps between screw splines at mullion intersections.


Designing for Moisture Protection

•  Water penetration resistance is a function of glazing details, frame construction and drainage details, weather stripping and frame gaskets, interior sealants (for operable windows, see Windows), and perimeter flashings and seals.

•  Water can enter the exterior wall system by means of five different forces: gravity, kinetic energy, air pressure difference, surface tension, and capillary action.

•  To mitigate water infiltration, all of these forces must be accounted for in the system design.


Designing for Moisture Protection

•  Unlike discontinuous windows, which are smaller units and can rely to a high degree on sill flashings to capture frame corner leakage, curtain walls cover large expanses of wall without sill flashings at each glazed opening. –  Water penetration of curtain wall frame

corners is likely to leak to the interior and/or onto insulating glass below.

–  Watertight frame corner construction and good glazing pocket drainage are critical for reliable water penetration resistance.


Designing for Thermal Load

•  Thermal loads are induced in a curtain wall system because the aluminum framing system has a relatively high coefficient of thermal expansion. This means that over the span of a couple of floors, the curtain wall will expand and contract some distance, relative to its length and the temperature differential.

•  This expansion and contraction is accounted for by cutting horizontal mullions slightly short and allowing a space between the horizontal and vertical mullions.

•  In unitized curtain wall, a gap is left between units, which is sealed from air and water penetration by wiper gaskets. Vertically, anchors carrying wind load only (not dead load) are slotted to account for movement.

–  This slot also accounts for live load deflection and creep in the floor slabs of the building structure.


Designing for Wind Load •  Wind load is the pressure from wind that must

be resisted by the curtain wall to protect the building.

•  Wind loads vary greatly throughout the world, with the largest wind loads being near the coast in hurricane-prone regions.

•  Building codes are used to determine the required design wind loads for a specific project location.

•  Often, a wind tunnel study is performed on large or unusually shaped buildings. A scale model of the building and the surrounding vicinity is built and placed in a wind tunnel to determine the wind pressures acting on the structure in question. These studies take into account vortex shedding around corners and the effects of surrounding buildings.


Designing for Dead Load

•  Dead load is defined as the weight of structural elements and the permanent features on the structure. In the case of curtain walls, this load is made up of the weight of the mullions, anchors, and other structural components of the curtain wall.

–  Additional dead loads imposed on the curtain wall, such as sunshades, must be accounted for in the design of the curtain wall components and anchors.


Designing for Snow Load

•  Snow loads and live loads are not typically an issue in curtain walls, since curtain walls are designed to be vertical or slightly inclined. –  If the slope of a wall exceeds 15 degrees, these loads will need to be

considered.


Designing for Seismic Load •  Seismic loads need to be addressed

in the design of curtain wall components and anchors. In most situations, the curtain wall is able to naturally withstand seismic and wind induced building sway because of the space provided between the glazing infill and the mullion.

•  In tests, standard curtain wall systems are able to withstand three inches (75 mm) of relative floor movement without glass breakage or water leakage. Anchor design needs to be reviewed, however, since a large floor-to-floor displacement can place high forces on anchors.


Designing for Blast Load

•  Accidental explosions and terrorist threats have brought on increased concern for the fragility of a curtain wall system in relation to blast loads.

–  The bombing of the Alfred P. Murrah Federal Building in Oklahoma City, Oklahoma, has spawned much of the current research and mandates in regards to building response to blast loads. Currently, all new federal buildings in the U.S., and all U.S. embassies built on foreign soil, must have some provision for resistance to bomb blasts.


Designing for Blast Load •  Since the curtain wall is at the exterior of the building, it becomes the first line of

defense in a bomb attack. As such, blast resistant curtain walls must be designed to withstand such forces without compromising the interior of the building to protect its occupants.

–  Since blast loads are very high loads with short durations, the curtain wall response should be analyzed in a dynamic load analysis, with full-scale mock-up testing performed prior to design completion and installation.

•  Blast resistant glazing consists of laminated glass, which is meant to break but not separate from the mullions. Similar technology is used in hurricane-prone areas for the protection from wind-borne debris.

Anchorage: designed to transfer loads to structure

Curtain wall system: engineered to take advantage of inherent flexibility

Laminated glazing to restrain debris and develop membrane resistance Glazing adhered to mullion with structural silicone sealant to transfer collected loads to frames



•  Curtain walls can be classified by their method of fabrication and installation into two general categories.

–  Stick systems –  In a stick system, the mullions are installed first, and

then the glass panels are inserted into the mullion framing in the field.

–  The primary advantage of this system is it's lower cost when compared to the unitized system.

–  Unitized or modular systems. –  In a unitized system the mullions are fabricated with the

glass panels in place, and then erected as individual panels.

–  The primary advantages of the unitized system are reduced construction time, better quality control and increased structural flexibility resulting from the gasketed joints in the unitized panels.

–  Both the unitized and stick-built systems are designed to be either interior or exterior glazed systems. Interior and exterior glazed systems offer different advantages and disadvantages.


Curtain Wall System Design

•  Interior glazed systems allow for glass or opaque panel installation into the curtain wall openings from the interior of the building.

–  Interior glazed systems are typically specified for applications with limited interior obstructions to allow adequate access to the interior of the curtain wall.

–  For high-rise construction interior glazing is sometimes used due to access and logistics of replacing glass from a swing stage.


Curtain Wall System Design

•  In exterior glazed systems, glass and opaque panels are installed from the exterior of the curtain wall.

–  Exterior glazed systems require swing stage or scaffolding access to the exterior of the curtain wall for repair or replacement.

–  For low rise construction with easy access to the building, outside glazing is typically specified.


Curtain Wall Systems – Stick-Type Construction •  The vast majority of curtain walls are installed

long pieces (referred to as sticks) between floors vertically and between vertical members horizontally.

–  Framing members may be fabricated in a shop environment, but all installation and glazing is typically performed at the jobsite.

•  In the stick system, the curtain wall frame (mullions) and glass or opaque panels are installed and connected together piece by piece.

•  Single or double story-height vertical framing members are installed first by attaching to floor slabs or other lateral structural elements.

•  Intermediate horizontal framing members are installed between the verticals and the process repeats itself as the installation progresses.


Curtain Wall Systems – Unitized Construction •  In the unitized system, the curtain wall is composed

of large units that are assembled and glazed in the factory, shipped to the site and erected on the building.

•  Vertical and horizontal mullions of the modules mate together with the adjoining modules. Modules are generally constructed one story tall and one module wide but may incorporate multiple modules.

–  Typical units are five to six feet wide. •  A unitized curtain wall has the advantages of speed;

lower field installation costs; and quality control. •  Where stick systems require multiple steps to erect

and seal the wall, unitized walls arrive on the site completely assembled allowing the floors to be closed in more quickly.

•  The advantages of the unitized system derive from the more reliable seals achievable from factory construction and the reduced cost of labor in the factory versus that of high rise field labor. Units can be assembled in a factory while the structural frame of the building is being constructed.


Unitized Curtain Wall Systems

•  The units should be completely assembled in a factory and shipped to the site for installation on the building.

•  The units are placed on the floors, bundled in crates, using the tower crane and lowered into place using a smaller crane or hoist owned by the glazing contractor.

•  Unitized systems also require less space on site for layout thus providing an advantage for urban sites with space limitations.


Unitized Curtain Wall Systems •  Unitized systems generally rely on rain screen design principles and

gaskets and/or the interlock of mating frames for moisture protection at joints between adjacent modules.

•  The interlocking legs of the horizontal mullions are the most critical interface of a unitized system.

•  Water that infiltrates the interlocking vertical mullions drains to the interlocking horizontals that must collect and divert this water to the exterior.



•  The interlocking vertical mullions will typically have two interlocking legs. One leg will be in the plane just behind the glazing pocket and the other at the interior face of the mullions. –  The interlocking leg in the plane of the

glazing pocket will be sealed by gaskets and is the primary line of defense against water and air infiltration.

–  More robust systems will also include a gasket at the interior interlock. Systems whose connecting legs lock also compromise the ability of the system to accommodate movement.



•  While two story spans are feasible, the weight of the unit is doubled which may require increased structural capacity to accommodate the increased load.

–  Wind load bracing should be incorporated at the single span height to avoid increasing the vertical mullion dimension to accommodate the increased span.

•  Steel can be added to a unitized system to increase its spanning capability. However, unlike a stick system which has an integral hollow shape, the split mullions must be allowed to move independently to accommodate the building movement thus complicating the introduction of steel. Large units may also increase transportation costs from the factory to the site and erection costs of placing the units on the building.


Commercial Glazing System Components

•  Spacers (Shims) –  Small blocks of neoprene, or other approved material, placed

on each side of the glass product to provide glass centering, maintain uniform width of sealant bead, and prevent excessive sealant distortion.

•  Setting Blocks –  Rectangular, cured extrusions of neoprene rubber or other

approved material on which the glass product bottom edge is placed on glazing to effectively support the glass weight.

•  Stops –  The stationary lip of the back of the glazing channel and

removable molding (retainer) at the front of the glazing channel.

•  Structural Glazing Gaskets –  Cured elastomeric channel-shaped extrusions used in place of

a conventional sash to install glass products onto structurally supporting sub-frames with the pressure of sealing exerted by the insert of separate lock-strip wedging splines.


Inferior Glazing System Construction

Interior removable stops flush with the glazing sill.

Fastener penetrations through the glazing pocket allow leakage into the wall cavity below. If sill flashing is present, fasteners set through the glazing pocket will puncture the flashing and cause leakage.

The flat sill allows water to pond and increases the risk of leakage. Missing sill flashing allows water leakage into the wall cavity.

Without an integral return edge, the frame provides inadequate bonding substrate for the perimeter sealant.

A poorly configured perimeter seal will not be durable and will promote leakage past the window jamb.

The lack of weep holes in the glazing pocket allows water accumulation and promotes IG unit and laminated glass failure

Without proper edge-blocking, the IG unit may “walk”, resulting in glass-to-frame contact and the potential for glass edge damage or breakage


Improved Glazing System Construction

The sill flashing is sloped with upturned end dams to collect water that has penetrated the glazing system and drain it to the exterior.

The perimeter of the window frame includes substantial return legs that provide adequate bonding surfaces for a properly configured sealant joint at the window perimeter.

Fixed stop on the interior above the sill line.

Setting blocks support the weight of the IG unit preventing glass-to-frame contact and reducing the risk of glass breakage.

Gravity load shims support the weight of the IG unit.

The wet glazing seal on the exterior provides better water penetration resistance than dry glazing (gaskets), but requires access from the exterior for glazing removal.

The window sill frame is attached through the back to a structural clip angle, to avoid fastener penetration of the horizontal portion of the sill flashing.

1.  The glazing pocket weep holes drain water that penetrates the glazing seals. A well-drained glazing pocket prolongs the service life of the insulating glass (by reducing the exposure of edge seals to water), and reduces interior leakage.

The anti-walk pad at the window jamb prevents the glass from "walking" in the glazing pocket and contacting the metal frame.


Commercial Glazing Techniques

•  Wet glazing –  Pre-formed tape –  Gunable elastomeric sealants

•  Dry glazing •  Wet / dry glazing •  Pressure glazed systems •  Structural glazing

–  Silicone –  Acrylic foam tape

•  Butt-joint glazing


Wet Glazing Types

•  Preformed tape –  Generally an elastomeric material extruded

with or without a continuous integral shim. The tape comes on a roll with a release paper on one side. It should be applied to a properly prepared, clean, dry surface not more than 24 hours prior to glazing. The release paper should not be removed until the glass in ready to be installed.


Wet Glazing Types

•  Gunable sealants –  There are two types of gunable sealants for

use in glazing applications, non-curing and curing. –  Non-curing gunable sealants remain soft and tacky,

whereas curing sealants become a semi-firm piece of synthetic rubber. Non-curing gunable sealants are usually used as a metal-to-metal joint sealant in non-exposed locations. When using the non-curing type, the tacky surface can quickly collect dirt and become unsightly if used in an exposed location.

–  Curing gunable sealants are materials such as the polysulfides, silicones, urethanes, acrylics and other synthetic polymers. They cure to a resilient state by chemical reaction with external forces such as temperature and humidity or by solvent release. They should be used as a gunned-in-place glazing sealant or cap bead.


Wet Glazing

•  Wet glazing materials can be classified into two primary categories: Pre-formed tape and gunable elastomeric sealants.

•  Lateral shims are normally required with wet glazing materials to center the glass in the opening and to hold the glass in position when subjected to wind load, vibration or building movement.

•  Wet glazing most commonly consists of cap bead of a gunable ("wet") sealant installed over a preformed tape or gasket.

•  Joints should be lightly daubed with a compatible gunable sealant to ensure a positive seal. The only joints in the tape should be at the corners.


Dry Glazing

•  Dry glazing is the common designation for systems utilizing extruded rubber gaskets as one or both of the glazing seals.

•  This system is also referred to as compression gasket glazing because the system relies on compression of the glazing gasket to seal against air infiltration and water penetration.

•  In this system the glass is installed from the interior of the building, eliminating the need for substantial scaffolding and saving money.

•  Dry glazing is popular because its performance is not as affected by installation, weather, workmanship and compatibility issues as with wet glazing systems.


Wet / Dry Glazing

•  Wet / dry glazing is simply a combination of we glazing and dry glazing design.

•  Wet / dry systems are most commonly installed with exterior wet glazing and interior dry glazing.

•  Cap beads are generally applied around the exterior perimeter of the glazing.

•  The primary purpose of the cap bead is to make the glazing water and weather-tight.


Wet Vs. Dry Glazing

Replacement intervals for dry gaskets and cap beads of wet glazed systems are about equal.


Pressure Plate Glazing •  Pressure plate glazed systems take their

name from the fact that the pressure or compression required to achieve weather tightness is mechanically applied.

•  In this type of glazing system, the glass panels are installed from the exterior, typically against dry gaskets.

•  The outer layer of gaskets is installed and the gaskets are compressed against the glass by the torque applied to fasteners securing a continuous pressure plate. The plate is later typically covered with a snap-on mullion cover.

•  This system provides reasonable performance but is susceptible to leaks at corners or joints in dry gaskets.

•  For improved performance four-sided gaskets can be fabricated at additional cost or wet sealants can be installed to provide a concealed interior toe bead or exposed interior cap beads.


Structural Silicone Glazing •  In structural silicone glazing (SSG) systems,

the glass is bonded to the framing members of a curtain wall utilizing a structural silicone adhesive / sealant without the presence of outdoor retainers or stops.

–  SSG systems are described as two or four-sided systems, in reference to the number of sides that are supported by structural silicone sealant.

•  Outer silicone weather seals supplement the structural seal. Unitized systems are frequently structural silicone glazed, especially if four-side structural silicone glazing is desired.

•  Two-sided systems can be designed to be either shop or field-glazed, whereas four-sided systems should be designed to be shop glazed.


Acrylic Foam Tape Structural Glazing

•  In acrylic foam tape (AFT) structural glazing systems, the glass is bonded to the framing members of the curtain wall utilizing acrylic foam tape.

–  These tapes provide acrylic adhesive throughout the entire tape construction including the foam core.


Acrylic Foam Tape Structural Glazing

•  Acrylic foam tape glazing is typically used on single story commercial window systems such as storefronts. The main role of the acrylic foam structural glazing tape is to act as the primary bonding agent of the glass to the metal frame.

•  The basic guidelines for acrylic foam tape structural glazing are the same as for structural silicone glazing systems.

•  Acrylic foam structural glazing tapes should only be used on factory glazed projects.


Butt-Joint Glazing •  Butt-joint glazing is a method of installing glass to provide wide horizontal areas of

vision glass without the interruption of vertical framing members. •  This glazing technique incorporates a captured head and sill glazing, using metal or

wood retaining members with a combination of wet or dry sealants. •  Vertical glass edges are spaced slightly apart and sealed with silicone sealant. The

sealant serves only as a weather stop at the vertical joints; therefore, this vertical glass and sealant joint cannot be considered to be structural.

•  The design and execution of a butt-joint glazing installation requires more attention to detail than does a conventional systems with vertical framing members.

•  The glass is supported on only two edges, so deflection and glass stressing under design load will be substantially greater than with four edges supported.

•  Insulating glass is not suitable for butt-joint glazing because as the glass deflects, sealants are placed in extreme shear along the unsupported edge. Installation in a butt-joint glazing application will void an IG fabricator’s warranty.

•  Typically, a minimum of 3/8” (10mm) thick glass is recommended for butt-joint glazing applications. Thicker glass reduces the potential for deflection.

•  Heat-treating glass will not reduce deflection. The inherent warp of heat-treated glass increases the difficulty in executing a proper vertical silicone joint.


Glass Fabrication Sloped Glazing

SILICONE WEATHER

SEAL

STRUCTURAL SILICONE

SEALS

INTERIOR

EXTERIOR

> 15°


Commercial Glazing System Guideline Summary •  Since glass itself is impervious to water penetration, glazing waterproofing

performance is determined by the glazing method chosen (e.g. wet glazing versus dry glazing) and drainage details of the framing system.

•  For maximum water tightness, a wet-glazed system, consisting of pre-shimmed butyl tape glazing tape and silicone cap bead, should be specified.

•  Glazing sealants cannot exclude all water, so providing internal drainage is critical.

•  The durability of IG units is dependent on the quality of the hermetic seal and the level of protection from water afforded by the glazing seal and the window frame system.

–  Dual seal units (butyl-based primary seal and silicone secondary seal) are more reliable and more durable than single-seal systems. Continuity and uniformity of both primary and secondary seals is critical.

–  The spacer should be filled with desiccant and constructed with bent, welded, or soldered corners rather than corner keys.


Commercial Glazing System Guideline Summary

•  Setting blocks must be properly sized and located (min. 1/4 inch thick) to raise the edge of the IG unit glass above water level in the glazing pocket.

•  The setting blocks must be wide enough to support the entire IG unit cross section and be notched to allow water to drain toward the weep holes. Setting block material must be chemically compatible with the IG unit secondary seal.

•  The frame design must promote water drainage away from IG unit through the incorporation of sloped glazing pockets, large diameter weep holes, and drainage within each glazing opening.


XI – Sales Training Commercial Glass Products


2012 Global Glass Markets Total 2012 Global Available Market ($ mil)

Residential, $8,700

Commercial, $15,400

Interiors, $400

Interiors non-mirror, $600

Energy, $800Electronics, $200

Automotive, $23,600

Other, $23,700

Total 2012 Global Available Market - Annual Growth

Flat, 6.9%

Residential, 4.9%

Commercial, 6.0%

Interiors, 4.9%

Interiors non-mirror, 4.9%

Energy, 25.0%

Electronics, 7.0%

Automotive, 3.3%

Other, 5.5%


Photovoltaics (PV)

•  Solar cells, also called photovoltaic (PV) cells, convert sunlight directly into electricity. PV gets its name from the process of converting light (photons) to electricity (voltage), which is called the PV effect.

•  When light shines on a PV cell, it may be reflected, absorbed, or transmitted, but only the light that is absorbed by the cell generates electricity.

•  Individual PV cells are connected together to form PV modules that may be up to several feet long and a few feet wide. Modules, in turn, can be combined and connected to form PV arrays of different sizes and power output. For large electric utility or industrial applications, hundreds of solar arrays are interconnected to form a large utility-scale PV system.

•  PV panels are not highly efficient, converting only 12-15% of the sun’s light into electricity, so without efficiency improvements, the only way to increase power generation is by building larger and larger PV arrays.


Photovoltaics (PV)

•  Traditional solar cells are made from silicon, are usually flat, and generally are the most efficient.

•  Second-generation solar cells are called thin-film solar cells because they are made from amorphous silicon or non-silicon materials such as cadmium telluride. Thin film solar cells use layers of semiconductor materials only a few micrometers thick.

•  PV cells can be made of many different semiconductors including crystalline silicon, thin-film, concentrating PV and BIPV (building integrated photovoltaic) systems.

•  These systems incorporate transparent and non-transparent conductive coatings applied to solar glass to maximize output and conversion efficiencies.

•  Improving the efficiency of the coatings and substrates that represent the core of the solar cell will be critical to future advances in PV technology,


Technology is fragmented with many types of systems including glass tubes and polymer based systems

Thermal Hot Water


Fresnel Collector

Parabolic Dish Central

Receiver

Concentrating PV

Parabolic Trough

Concentrating Solar Power (CSP) Technologies


Parabolic Trough Mirrors •  Monolithic Parabolic Trough Mirrors

–  Proven mirror technology –  Durable 3-layer paint system –  > 93% Total Solar Reflectance –  Heat Strengthened Glass

•  Laminated Parabolic Trough Mirrors –  Industry’s only laminated CSP Solution –  Guardian owns technology patent rights –  > 94.5% Total Solar Reflectance –  High durability mirror that reduces breakage

and wind load issues

4 mm low iron 2nd surface mirror

Mounting pad glued to

protective coating

3 layer protective

coating

1.6mm low iron 2nd surface mirror

2.3mm green glass

Mounting pad

PVB


Fresnel CSP Systems

•  Primary Mirrors –  An array of flat, angled, second surface

mirrors are anchored to a common substructure

–  Computer-controlled system that tracks the sun throughout the day and repositions mirrors for maximum solar exposure.

–  Mirrors direct solar energy at a cluster of water-filled receiver tubes overhead, creating pressurized steam that drives an electricity-generating turbine.

•  Secondary Reflector –  Complex half circle SSM reflector –  Requires sputtered Ag-based SSM for

bending –  Guardian is proposing a laminated design

•  High Transmission Protector Plate –  Solar Float with two sided AR coating –  Sol-Gel AR Coating required for secondary

reflector

Flat angled mirrors

Receiver Tubes


Vacuum Insulating Glass (VIG) •  Vacuum-insulated glass (VIG) uses two layers of low-e glass which are separated by

an extremely thin air space. Approximately 250 microns (0.25 mm) . •  Between the two layers stands a series of extremely small pillar supports which are

nearly invisible . These pillars keep the two panes of glass from drawing together and touching each other once a vacuum is applied.

•  After a vacuum is applied, the unit is hermetically sealed. This method of construction achieves an insulating factor of R-10 or higher.

approx. 0.25 mm evacuated air space


Aerogels

•  Silica-based, open-cell, foam-like material composed of about 4% silica and 96% air.

•  Lowest Density of any material. •  An ounce has the surface area of 10 football fields. •  Very lightweight and flexible. •  The microscopic cells of the foam entrap air (or

another gas if gas-filled), thereby preventing convection while still allowing light to pass (High light transmission, up to 70%).

•  Lowest refractive index of any material. •  Highest thermal insulation of any material. •  Long-wave thermal radiation is virtually eliminated

due to the multiple cell walls through which long-wave infrared radiation must be absorbed and reradiated.


Aerogels

•  The cell sizes are smaller than the mean free path of air/gas molecules, thus reducing conduction to values below those of pure conduction for the air/gas.

•  The particles that make up the thin cell walls slightly diffuse the light passing through, creating a bluish haze similar to that of the sky.

•  Invented 70 years ago but only viable since the 1990’s due to NASA .

•  Shock and sound resistant. •  Currently being used in skylight systems

coupled with polycarbonate. •  Very expensive and difficult to produce in

large quantities.


Organic Conductive Polymers

•  Organic conductive polymers are thin film coatings which are based on carbon molecules and have several advantages over other inorganic conductors. They are light weight, durable, flexible and less expensive. In most instances however, organic conductive polymers have a higher resistance and do not conduct electricity as efficiently as inorganic conductors.

•  New applications being explored include smart windows which could adjust themselves to environmental condition changes. Conductive polymers are expected to play an important role in many future glass applications in the future.


Active Matrix Organic Light Emitting Diodes (AMOLED) •  Active Matrix Organic Light Emitting Diodes (AMOLED) is the latest technology in

extremely light weight, flexible, thin film coating display designs. •  In addition to ultra-sharp imaging and high contrast, AMOLED coating retains

approximately 40% transparency. AMOLED display viewing angles are far wider than a typical LCD display and require no backlighting which makes their power consumption much lower than LCD modules and increases battery life for portable products.

•  Because of the wide viewing angle, high contrast, low power consumption and flexibility and small size, OLEDs become ideal for portable applications. Three dimensional AMOLED applications are currently under development


Switchable Glazing Technologies Provide A Range Of Optical And Energy Performance

•  Switchable glazing provides day lighting in transparent state and privacy and / or energy performance in the translucent state

•  Three primary technologies for switchable glass –  Electro chromic (EC) –  Suspended Particle Device (SPD) –  Liquid Crystal Display (LCD)

•  Current market prices range from •  $100-$300 ft.2

–  The goal is < $30 ft2

•  Initial launch market –  Automotive Sunroofs and visors for –  premium vehicles


Electrochromic (EC) Technology

•  Electrochromics operate based on the principle of ion movement between electrical fields.

–  When a low voltage is applied across the conductors, ions move from the ion storage layer, through the ion conducting layer and into the electrochromic layer causing the assembly to change optical and thermal properties.

–  Reversing the voltage reverses this process, restoring the device to its previous clear state.

•  Flip a switch and an electrochromic window can change from clear to fully darkened or any level of tint in-between.

–  The glass may be programmed to absorb only part of the light spectrum.

–  EC windows provide privacy, glare reduction, and reduced solar heat gain.

•  Disadvantages of EC technology include slow response time, size limitations, UV degradation, and the requirement of a coating with a sheet resistance < 1.5 ohm/sq


Suspended Particle Device (SPD)

•  SPD technology operates on the principle of electrically controlled light scattering.

–  SPDs consist of microscopic molecular particles suspended in a liquid solution. The particles are placed in a conductive sheet that is sandwiched between two panes of glass.

–  When electricity comes into contact with the SPDs they instantly line up in a straight line and allow light to flow through. Once the electricity is taken away, they move back into a random pattern and block light.

•  Several control methods are possible with the SPD light-control windows, including rheostat or remote for manual control, or with photocells and other sensing devices to automatically control the level of light.

•  Advantages of SPD technology include fast response time and minimal size limitations

•  The primary disadvantages of traditional SPD technology are performance and aesthetic degradation with UV exposure, and high manufacturing cost.


Polymer Dispersed Liquid Crystal (Nematic PDLC) •  PDLCs operated on the principle of electrically

controlled light scattering. –  Liquid crystal is supported by thermoplastic polymer

which is laminated with traditional PVB to create a large area switchable glass system

•  Rapid change between transparent and opaque states

–  Provides desired day lighting level in the transparent state.

–  Provides desired privacy / security in the opaque state. •  Intensity of image can be varied and controlled. •  Familiar laminated glass manufacturing process

–  Scalable, Bendable, Meets impact standards –  Provides sound attenuation

•  Uses standard household electricity –  Simplified connector assembly

•  Equivalent ≥ 15 year field life expectancy •  Market price ≤ $30 ft.2

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