protecting and preserving wood. next generation science / common core standards addressed! whst.9...

Protecting and Preserving WoodProtecting and Preserving Wood

Next Generation Science / Common Core Standards Addressed!Next Generation Science / Common Core Standards Addressed!

WHST.9‐12.9 Draw evidence from informational texts to support analysis, WHST.9‐12.9 Draw evidence from informational texts to support analysis, reflection, and research. (HSLS1‐6)reflection, and research. (HSLS1‐6)

Why and how do organisms interact with Why and how do organisms interact with timber and cause decay?timber and cause decay?

Look at the available samples and Look at the available samples and determine if decomposers are determine if decomposers are present.present.

Explain the physical characteristics Explain the physical characteristics of the decomposing wood.of the decomposing wood.

Identify ways to protect wood Identify ways to protect wood species from decay.species from decay.

Bell Work / Learning ObjectivesBell Work / Learning Objectives

1. Explain the principal causes of wood 1. Explain the principal causes of wood deterioration.deterioration.

2. Identify commercial and noncommercial 2. Identify commercial and noncommercial wood preservatives.wood preservatives.

3. Identify naturally durable woods.3. Identify naturally durable woods. 4. Describe preservatives used for wood.4. Describe preservatives used for wood. 5. Explain the non-pressure preservative 5. Explain the non-pressure preservative

treating processes.treating processes.

TermsTerms

Coal-tar creosoteCoal-tar creosoteCold-soakingCold-soakingDouble-diffusionDouble-diffusionHeartwoodHeartwoodHot-cold bathHot-cold bathSapwoodSapwoodSurface checkSurface check

What causes wood to deteriorate?What causes wood to deteriorate?

Like many other materials, Like many other materials, wood deteriorates as a wood deteriorates as a result of interaction with the result of interaction with the environment. Moisture and environment. Moisture and insects are primary enemies insects are primary enemies of wood/lumber. of wood/lumber.


A. Wood exposed to fungi, damp or A. Wood exposed to fungi, damp or moist places, or certain insects will moist places, or certain insects will deteriorate.deteriorate.• 1. Wood products placed near the surface 1. Wood products placed near the surface

of the ground are very susceptible to decay of the ground are very susceptible to decay and to destruction by insects.and to destruction by insects.

• 2. In general, all wood contacting the 2. In general, all wood contacting the ground or exposed to weather should be ground or exposed to weather should be treated with a preservative.treated with a preservative.

What causes wood to deteriorate?What causes wood to deteriorate? Using a preservative is even more important in Using a preservative is even more important in

regions where high rainfall and mild climate are regions where high rainfall and mild climate are factors.factors.

For example wood would tend to rot faster in Red For example wood would tend to rot faster in Red River New Mexico than it would in Deming NM.River New Mexico than it would in Deming NM.


When planning a project made of When planning a project made of wood or that will utilize wood, wood or that will utilize wood, following accepted precautions will following accepted precautions will reduce the chances that the wood reduce the chances that the wood will deteriorate prematurely.will deteriorate prematurely.• 1. 1. Consider conditions that present Consider conditions that present

potential decay or insect problemspotential decay or insect problems..


Design and treat new construction Design and treat new construction to protect wood from moisture, to protect wood from moisture, decay hazards, and insects.decay hazards, and insects.


Use treated wood in Use treated wood in constructions where wood constructions where wood cannot be kept at least 18 cannot be kept at least 18 inches above the surface inches above the surface of the ground and of the ground and protected from excessive protected from excessive moisture. moisture.

Treat exposed large load-Treat exposed large load-bearing beams with bearing beams with preservative.preservative.

What causes wood to deteriorate?What causes wood to deteriorate? Recognize that preservative is Recognize that preservative is

essential where wood in essential where wood in permanent structures is in permanent structures is in contact with ground.contact with ground.

5. When wood decay is 5. When wood decay is detected, immediately remove detected, immediately remove moisture from the wood so moisture from the wood so decay does not worsen. decay does not worsen. • Decay causing fungi grow Decay causing fungi grow

even when there is only a even when there is only a little moisture on the surface little moisture on the surface of wood cells.of wood cells.

What causes wood to deteriorate?What causes wood to deteriorate? Obtain professional advice, if needed, Obtain professional advice, if needed,

through the local state forestry agencies, through the local state forestry agencies, county and city statutes and construction county and city statutes and construction codes.codes.

Remember that new construction should be Remember that new construction should be inspected, especially when building within the inspected, especially when building within the city limits.city limits.

What are the commercial and What are the commercial and noncommercial wood preservatives?noncommercial wood preservatives?

The purpose of treating wood is to The purpose of treating wood is to protect it against insects and decay protect it against insects and decay organisms.organisms.• Wood that is commercially pressure treated with Wood that is commercially pressure treated with

a good preservative can be expected to give the a good preservative can be expected to give the most dependable service and a long life.most dependable service and a long life.


Pressure treatment requires Pressure treatment requires expensive equipment and highly expensive equipment and highly technical skills.technical skills.

The wood to be treated is placed in The wood to be treated is placed in a steel cylinder and sealed. a steel cylinder and sealed. • A preservative is pumped into the A preservative is pumped into the

cylinder, and pressure and/or vacuum cylinder, and pressure and/or vacuum is applied so that the wood absorbs is applied so that the wood absorbs the desired amount of preservative.the desired amount of preservative.


Wood can treated at home with good results Wood can treated at home with good results by proper use of recognized toxic by proper use of recognized toxic preservative.preservative.

Good preservatives applied poorly or poor Good preservatives applied poorly or poor preservatives applied carefully are of little preservatives applied carefully are of little value.value.

• The goal of preservative protects wood The goal of preservative protects wood from dangerous fungi and insects.from dangerous fungi and insects.


A good preservative must do a number things.A good preservative must do a number things.• It must penetrate the wood to sufficient depth to form an It must penetrate the wood to sufficient depth to form an

exterior shell of poisonous wood that will prevent attacks exterior shell of poisonous wood that will prevent attacks by fungi and insects, even in surface defects that may by fungi and insects, even in surface defects that may later develop.later develop.

• It must retain its toxic effect under field conditions for a It must retain its toxic effect under field conditions for a number of years.number of years.

• It should not easily leach out of the wood.It should not easily leach out of the wood.• It must not be flammable or corrode metal.It must not be flammable or corrode metal.• It should not be harmful to humans or pets when used in It should not be harmful to humans or pets when used in

normal concentrations.normal concentrations.• It must be handled and applied safely according to It must be handled and applied safely according to

directions.directions.


b. It must retain its toxic effect under b. It must retain its toxic effect under field conditions for a number of field conditions for a number of years.years.

c. It should not easily leach out of c. It should not easily leach out of the wood while in service.the wood while in service.

d. It must not be flammable or d. It must not be flammable or injurious to the wood, or corrode injurious to the wood, or corrode metal.metal.


Lumber treated with preservatives Lumber treated with preservatives should be handled cautiously. should be handled cautiously.

Always wear skin and eye protection Always wear skin and eye protection when handling treated lumber. when handling treated lumber.

Protection from breathing the sawdust Protection from breathing the sawdust when cutting treated lumber is when cutting treated lumber is necessary.necessary.


4. Treated lumber should not be 4. Treated lumber should not be used for interior applications.used for interior applications.

5. Treated lumber should be sealed 5. Treated lumber should be sealed with paint or polyurethane after with paint or polyurethane after construction. construction. • To prevent the preservative from To prevent the preservative from

being leached out.being leached out.


Preservatives such as coal-tar creosote, Preservatives such as coal-tar creosote, solutions of creosote mixed with other toxic solutions of creosote mixed with other toxic chemicals, pentachlorophenol (penta) chemicals, pentachlorophenol (penta) solutions, and water-borne materials solutions, and water-borne materials containing one or more compounds of containing one or more compounds of copper, zinc, fluorine, and chromium bring copper, zinc, fluorine, and chromium bring good results. good results.

These solutions are normally used for posts, These solutions are normally used for posts, poles, pilings and other heavy timbers.poles, pilings and other heavy timbers.


However, coal-tar creosote and However, coal-tar creosote and pentachlorophenol are only pentachlorophenol are only available for purchase and use by available for purchase and use by properly licensed users.properly licensed users.

What are the naturally durable woods?What are the naturally durable woods?

The natural durability of a given The natural durability of a given wood is determined by what part of wood is determined by what part of the tree it is taken from.the tree it is taken from.

The sapwood of trees is not durable when it is in The sapwood of trees is not durable when it is in contact with the soil. contact with the soil.

Sapwood is the light-colored wood near the outer Sapwood is the light-colored wood near the outer portion of the tree.portion of the tree.• Have you ever noticed a fence post where the outer Have you ever noticed a fence post where the outer

layers buried in the ground have rotted away but the layers buried in the ground have rotted away but the heartwood material remains.heartwood material remains.


Sapwood is composed of living cells and Sapwood is composed of living cells and conducts water and minerals to the tree conducts water and minerals to the tree crown.crown.

Heartwood, the dark inner core of the tree, is Heartwood, the dark inner core of the tree, is composed of non-living cells and naturally composed of non-living cells and naturally resists decay better than the sapwood.resists decay better than the sapwood.

Heartwood is more resistant in some species Heartwood is more resistant in some species than others.than others.


The heartwood of several species is The heartwood of several species is considered naturally durable and, considered naturally durable and, though untreated, can be used in though untreated, can be used in areas where wood comes in contact areas where wood comes in contact with the ground.with the ground.


Black locust, black walnut, osage-Black locust, black walnut, osage-orange, catalpa, cedar, chestnut, orange, catalpa, cedar, chestnut, juniper, lighter or pitchy pine, pacific yew juniper, lighter or pitchy pine, pacific yew and white oak species are considered and white oak species are considered naturally durable.naturally durable.

Black locust, lighter pine, red mulberry, Black locust, lighter pine, red mulberry, pacific yew and osage-orange are pacific yew and osage-orange are considered the most durable woods.considered the most durable woods.

What preservatives are used for wood?What preservatives are used for wood?

Wood preservatives are used to Wood preservatives are used to preserve or extend the life of wood preserve or extend the life of wood and wood products.and wood products.

Wood preservatives can be divided Wood preservatives can be divided into two groupsinto two groups: : preservative oils preservative oils and water-borne salts.and water-borne salts.


Preservative oils have higher Preservative oils have higher resistance to leaching than do salts resistance to leaching than do salts and are more suitable for outdoor and are more suitable for outdoor exposure.exposure.


The following are examples of The following are examples of preservative oils.preservative oils.• 1. Coal-tar creosote, the most widely 1. Coal-tar creosote, the most widely

used industrial preservative, is a used industrial preservative, is a brownish or black oil made by distilling brownish or black oil made by distilling coal tar. coal tar. It is practically insoluble in water and has It is practically insoluble in water and has

proven to be the best preservative for proven to be the best preservative for wood that will come in contact with wood that will come in contact with water.water.


Creosote mixtures are made from Creosote mixtures are made from coal tar and are usually so toxic to coal tar and are usually so toxic to fungi that they can be diluted up to 50 fungi that they can be diluted up to 50 percent or more with other oils to percent or more with other oils to lower the cost of using the lower the cost of using the preservatives.preservatives.


Other creosotes include wood-tar, Other creosotes include wood-tar, water-gas-tar, and oil-tar. water-gas-tar, and oil-tar. • They have wood-preserving properties They have wood-preserving properties

when of good quality and properly when of good quality and properly used.used.

Coal tar alone is not a good Coal tar alone is not a good preserver. preserver. • It is not very poisonous to fungi and it It is not very poisonous to fungi and it

does not penetrate wood very well.does not penetrate wood very well.


Of the chlorinated phenols, Of the chlorinated phenols, pentachlorophenol or penta, has pentachlorophenol or penta, has gained wide acceptance as an gained wide acceptance as an effective wood preservative in cold effective wood preservative in cold soaking and in the hot-cold bath soaking and in the hot-cold bath process. process.

It is available in the dry flake form or It is available in the dry flake form or ready to use solution.ready to use solution.


Concentrated and ready to use Concentrated and ready to use solutions of copper naphthenate are solutions of copper naphthenate are available for mixing with petroleum available for mixing with petroleum oils to make a treating solution that oils to make a treating solution that is effective against termites and is effective against termites and decay.decay. Microsoft.com


Water-borne salts generally do not Water-borne salts generally do not perform as well as preservative oils perform as well as preservative oils under conditions favorable to under conditions favorable to leaching.leaching.

Water borne salts are principally Water borne salts are principally used where wood will not be in used where wood will not be in contact with the ground.contact with the ground.


However, some water-However, some water-borne salts, such as borne salts, such as those used in the double those used in the double diffusion process, have diffusion process, have been developed to the been developed to the point where good point where good performance can be performance can be expected even when the expected even when the treated wood is in contact treated wood is in contact with the ground.with the ground.


Wood treated with water-borne Wood treated with water-borne preservatives is relatively clean, preservatives is relatively clean, paintable, and free of objectionable paintable, and free of objectionable odor.odor.


The following are examples of The following are examples of water-borne salts.water-borne salts.• Zinc chloride preservative is relatively Zinc chloride preservative is relatively

inexpensive, has no color, is uniform inexpensive, has no color, is uniform in quality and is not a fire hazard. in quality and is not a fire hazard. It will leach out of wood that is in contact It will leach out of wood that is in contact

with the soil and does not perform as with the soil and does not perform as well as other preservatives.well as other preservatives.


Chromated zinc chloride and Chromated zinc chloride and copperized chromated zinc chloride copperized chromated zinc chloride were developed as improvements were developed as improvements over zinc chloride. over zinc chloride.

They are more resistant to leaching.They are more resistant to leaching.


There are a number of commercially There are a number of commercially available patented preservatives available patented preservatives sold under the trade names of the sold under the trade names of the companies that make them. companies that make them. • They are principally used for the They are principally used for the

treatment of wood where there is not treatment of wood where there is not ground contact and where the treated ground contact and where the treated wood will be painted.wood will be painted.


Odor, paintability, color, and Odor, paintability, color, and combustibility are other factors to combustibility are other factors to consider when choosing a consider when choosing a preservative.preservative.

Summary / ReviewSummary / Review

1. Explain the principal causes of wood 1. Explain the principal causes of wood deterioration.deterioration.

2. Identify commercial and noncommercial 2. Identify commercial and noncommercial wood preservatives.wood preservatives.

3. Identify naturally durable woods.3. Identify naturally durable woods. 4. Describe preservatives used for wood.4. Describe preservatives used for wood. 5. Explain the non-pressure preservative 5. Explain the non-pressure preservative

treating processes.treating processes.

The End!The End!

protecting and preserving wood. next generation science / common core standards addressed! whst.9...

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