p&g research update hair color

Hair ColorResearch Update

contents

Hair Color History

1 Scientifi c BreakthroughsChemistry through the ages

2 Global ImpactHow hair color crosses cultures around the world

Biology Basics

2 Layer Up Hair composition, cycles, and the effects of color

3 Color Processes RevealedTemporary to permanent color possibilities

Chemistry At-a-Glance

4 Oxidative Dye FormulasThe components of conventional oxidative colorants

6 How Coloring Alters BiologyThe effect of coloring on the f-layer

6 Free Radical Formation — EDDS Addresses the HO* RadicalConsequences of hair colorant defi ned

Old Science vs. New Science

8 Carbonate + Glycinate = Hair Fiber IntegritySuperior color results with less damage

Hair Color Explored

10 Factors In Fading ColorMechanical to environmental causes investigated

10 Shine and ColorHuman perception of light refl ection

12 Conditioning BreakthroughModifi ed aminosilicones

13 Hair Color SafetyGovernment and research institute fi ndings

The Bigger Picture

13 Free Radical Formation Across Multiple DisciplinesHair color’s contribution to understanding these molecular culprits

14 P&G Research PartnershipsCross-discipline connections spur innovation

What’s Next?

14 Pigmentation BreakthroughsBiochemical infl uence on hair pigmentation

15 Summary

Hair Color: Research Update 1

Scientifi c Breakthroughs

Th e fi rst major breakthrough in hair coloring history came in 1863, when chemist Dr. August Wilhelm von Hofmann reported the dye properties of para-phenylenediamine (PPD). His discovery led to the birth of the synthetic hair dye industry, and PPD still dominates the fi eld today. Hofmann was also known for his studies of organic derivatives of ammonia and for discovering the fi rst unsaturated alcohol and several organic dyes.1

On the heels of Hofmann’s discovery, in 1867 London chemist E.H. Th i-ellay and Parisian hairdresser Leon Hugot demonstrated the advantages of hydrogen peroxide as a better chemical way to lighten hair than alkaline solutions. Th eir discovery soon became widely recognized, and oxidizing products remain the basis of bleaching preparations today. After the mid 1920s, oxidation dyes were greatly improved and the fashionable use of hair coloring boomed.2

Th e introduction of salon and then home hair dyes during the same period brought about a revolutionary change worldwide and an explosion of hair color options. Clairol’s founder, Lawrence M. Gelb, introduced hair color to salons more than 70 years ago when he discovered a European preparation and brought it to the U.S. When Clairol launched its fi rst salon colors in 1931, millions of women began using them. Instant Clairol Oil Shampoo Tint soon changed the look of Americans.3

In 1950, Clairol introduced Miss Clairol Hair Color Bath, the fi rst real breakthrough that lightened hair without the harshness and complicated handling of bleach. For the fi rst time, hair could be lightened, tinted, conditioned and shampooed in only one step instead of fi ve, in only 20 minutes. Within six months of this watershed discovery, hair coloring mania soared. Th e number of women going to the salon for permanent hair coloring increased

by more than 500 percent.4 Soon after, with the abundance of safe, inexpensive, easy-to-use products, home hair dying quickly grew in popularity.

Fast forward to 2007, where the next hair color breakthrough is currently unfolding, the fi rst in over 50 years. Advances in understanding the molecular structure of hair have allowed scientists to develop improved technologies that minimize the amount of damage in the coloring process, and even create specialized products that restore health and brilliance to colored hair. Th e new chemistry of hair color is here, making hair color easier, quicker, and more eff ective than ever.

Hair Color History

Beyond its biological function of keeping the head protected and

warm, hair’s true value lies in its ability to make a highly personal,

visual statement about oneself. Throughout history, hair color has

defi ned cultures, social status, professions, age and self-image; so

when humans discovered ways to change hair color, it signifi ed

a major step in self-expression. This self expression, however, has

always been infl uenced by innovative science.

2 Hair Color: Research Update

Biology BasicsLayer Up

Hair is composed of proteins (keratin) embedded in a sulphur-rich matrix encased in a sheath of overlapping scales. Hair has two distinct parts: the hair bulb (root), the biologically active part of hair where new hair is formed, and the shaft, the visible yet biologically inert part of hair that is sunk in a follicle beneath the skin. As cells in the base of the follicle are pushed up, they harden

and undergo pigmentation, the basis of hair color.8

Hair is made of three layers: the cuticle, cortex, and medulla. Th e cuticle consists of tightly packed, overlapping, colorless cells. Th e cortex contains varying amounts of two natural color pigments that determine a person’s hair color. It also supports the physical and mechanical properties of hair, and determines its tensile strength and texture. Th e medulla is typically a hollow shaft inside the hair. To permanently

Global Impact

Today, millions of women color their hair — spanning every age, race, nationality and religion. According to recent surveys, at least 88 percent of all women feel their hair has an eff ect on their self confi dence.5 Around the globe, the primary reason women color their hair is to look and feel better about themselves, feeling strongly that the products they use are fundamental in achieving this goal.6

With so many women taking such pride and care in their hair, the market is poised for a new scientifi c break-through. Today’s woman demands quick, effi cient product results that easily fi t into her hectic lifestyle, and hair color is certainly no exception. Today, hair color manufacturers have sophisticated research and development divisions that develop a broad range of advanced salon and home hair coloring products, addressing the complex needs of their consumers. Th ese advances can only be understood by starting with hair basics.

Agreement With Why Use Hair Color (Percent of Users Who Agree)7

UK Mexico China Russia USA

To feel better about myself 77 82 71 81 69

To feel more confi dent 65 76 67 79 50

To look and feel more attractive 61 71 52 84 62

To cover my gray 57 66 51 56 57

To cover root re-growth 57 81 55 73 not asked

History of Hair Color1200 BC: Some Egyptians use natural dyes to darken hair, such as kohl and henna, while others wear wigs to alter hair color, including Cleopatra.

1500s:Queen Elizabeth I redefi nes the standard of beauty in the West-ern World with her red hair and fair skin. Women all over Europe don red wigs to try and emulate the Queen.

1863: Chemist Dr. August Wilhelm von Hof-mann reports the dye properties of PPD. His discovery leads to the birth of the synthetic hair dye industry, and PPD still dominates the fi eld today.

1867: London chemist E.H. Thiellay and Parisian hairdresser Leon Hugot demonstrate the advan-tages of hydrogen perox-ide as a better chemical way to lighten hair than alkaline solutions.

1907: Eugene Schueller creates the fi rst blonde hair dye technology using PPD in Paris, becoming the first commercially available oxidative/permanent hair color.


densely packed melanin granules full of eumelanin pigment, while gray hair has no pigment at all.10

Hair follicles go through approximately 7-15 melanocyte seeding/replacement cycles in the average “gray-free” life span of 45 years. Th e average age of onset of graying for people of Cauca-sian descent is mid 30s, for people of Asian descent late 30s and for people of African descent mid 40s. By age 50, 50 percent of all people are likely to have 50 percent gray hair. Graying can happen gradually or suddenly, and gray hair may be more resistant to artifi cial color.11

Color Processes Revealed

At home or at a salon, the processes involved in coloring make the palette of possibilities limitless. Today’s hair color prod-ucts can remove (lift) natural hair color, add (deposit) a new color to natural color, or accomplish both processes at the same time. There are also products for adding

change the color of hair, a coloring product must be able to penetrate the cuticle to deposit or remove color in the cortex.9

Natural hair color depends on the amount and distribution of pigment (melanin) in the cortex, which is hereditary. Dark pigment, called eumelanin, is responsible for brown and black color, and pha-eomelanin produces blonde and red. Black hair, for example, contains

1931: The Clariol Company is established. Instant Clairol Oil Shampoo Tint soon changes the look of Americans.

1953: Wella develops the fi rst permanent cream colorants, offering women a less messy way to color their hair.

1980s:Demi-permanents closely resemble permanent products, but the levels of active ingredients are reduced. This prevents noticeable bleaching and slows down the penetration into the hair so that color is only formed in the outer part of the fi ber.

2003: Scientists develop a method to reduce damage from the HO* radical, and increase color formation by adding a chelant to hair color products called ethy-lenediaminedisuccinic acid (EDDS), which prevents copper formation on the hair shaft.

2007: Scientists develop a new bleach engine that signifi cantly reduces hair fi ber and f-layer damage and cuts the time it takes to color hair to ten minutes.

highlights, bleaching and toning to achieve drastic color changes, and glossing or glazing for more subtle changes.

Variation in chemistry allows fl exibility when it comes to levels of hair dyes.12

• Temporary (level 0) dyes or color rinses are acid dyes that do not diff use into the hair or bind fi rmly. Color coats the surface of the hair shaft but does not pen-etrate the cuticle, so the dye is easily washed out after the fi rst shampoo. While color results are limited, the dye may be a good option to test colors or to refresh dyed hair.

• Semi-permanent (level 1) prod-ucts use low-molecular-weight ingredients, such as nitroaromatic amines or aromatic dyes, but do not contain ammonia or peroxide. Color is already formed in the bottle. Th ese dyes gen-tly add color molecules to the cuticle layer, but do not bind

medulla

tip

cuticle

root

Hair follicle composition

fi rmly to the hair protein. Washing hair opens the cuti-cle, allowing color to escape. Conditioner smooths and closes the cuticle layer. Level 1 prod-ucts wash out typically between four and six shampoos. Th ey can make hair the same depth of color as the natural base or darker, but cannot lighten hair.

• Demi-permanent (level 2) and permanent (level 3) colors involve oxidative chemistry, during which the coloring components are mixed just before they are applied. Permanent dyes are the most important and most widely-sold commercial hair dyes. Th e primary diff erence between level 2 and level 3 products is the alkalizing agent and the concentration of peroxide.

º Demi-permanent colors wash out in up to 24 shampoos. Th ey can enhance and brighten natural color and blend or cover up grays. However, demi-permanent colors have little or no lightening potential. Since

they use about three percent hydrogen peroxide and a non-ammonia alkalizer, the cuticle does not swell as greatly with level 3 dyes, making dye penetration less effi cient.

º Permanent (level 3) colors, comprising 80 percent of the hair coloring market share, are the most versatile and long-last-ing and are available in the wid-est spectrum of shades.13 Th ese can lighten hair by two to three levels, change color in subtle or dramatic ways, and last until hair grows out. Th ey also provide 100 percent gray coverage, even on resistant grays. Re-application is recommended every four to six weeks to avoid noticeable regrowth.

Chemistry At-a-GlanceOxidative Dye Formulas

Most oxidative dye formulations contain two or more ingredients that act as dye precursors or couplers,


Level 0 Level 1 Level 3

Pigment deposition across different levels of hair dye


essential ingredients common to most permanent dyes. Th ey generally consist of p-diamines and p-amino-phenols. Precursors are oxidized to active intermediates when they have penetrated the hair shaft. Interme-diates then react with ingredients called color couplers to create wash-resistant dyes. Couplers modify the color produced by the oxidation of precursor compounds.

A conventional oxidative colorant is made up of two components which are mixed together directly before application to the hair.

• Dye Precursor / Alkalizer / ThickeningSystem — Th is component contains several ingredients, each with diff erent functions. Th ey are packaged together because they are completely compatible with each other and must be kept away from the oxidizing agent (hydrogen peroxide).

º Th e fi rst component is an alkaliz-ing agent (usually ammonia and/or an ammonia substitute such as monoethanolamine [MEA]). Th is has a number of roles in the hair colorant process:

– Swelling the hair fi ber to aid in diff usion of the dye precursors

– Raising the hair’s internal pH and ensuring that the overall dye mix has a high pH

– Facilitating the formation of the dyes within the hair fi ber and catalyzing melanin bleaching

º Th e second component is a mixture of dye precursors. Th ese are the ingredients that react together within the hair fi ber, resulting in the formation of color.

º Th e third is a surfactant (and optionally polymer) thickening system that provides the solubilization of the fi rst two components (particularly the dyes) and, when mixed with the H2O2 component (below)

provides the fi nal viscosity to hold the product on the hair fi bers without mess and dripping into the eyes, and if applicable, is tailored to work optimally with any application or mixing device supplied with the product.

• Hydrogen Peroxide Oxidant — It is essential that this component be kept at a low pH for storage to ensure stability; but it is only at high pH that bleaching and dyeing occurs. Th is component may also contain polymers or surfactants that thicken when

Common Hair Colorant Ingredients & Their Functions

Component Function Sample Ingredients

Solvent Dye vehicleWater, Propylene glycol, Ethanol, Glycerin

Surfactant Foaming, thickeningSodium lauryl sulfate, Ceteareth-25, Cocoamide MEA, Oleth-5

Alkali Swell hair, bleaching Ammonia, Monoethanolamine

Buffer Stabilize, reproducible Disodium phosphate, Citric acid

Dye precursors Impart colorP-Aminophenol, 1-Naphtol, P-Phenyl-enediamine, 4-Amino-2-hydroxytoluene

Fatty alcohols Emmolients Glyceryl stearate, Cetearyl alcohol

Quaternary compounds Conditioning Polyquaternium, Cetrimonium chloride

Peroxide Oxidant, bleaching Hydrogen peroxide


mixed with the high pH tint, and/or provide conditioning and rinsing benefi ts when the combined dye mass is rinsed from the hair. Hydrogen peroxide plays the following roles:

o A source of oxidizing agent for catalyzing the reaction of dye precursors

o Dispersing and solubilizing the hair’s natural pigment, melanin, while bleaching the hair’s natural pigment and any previous artifi cial colorant present in the hair fi ber

Once these components are mixed and applied to the hair surface, two complementary processes take place: bleaching the hair’s natural pigment and other artifi cial pigments present in the hair, and diff usion of dye precursors into the hair, followed by coupling reactions that result in the formation of chromophores within the hair fi ber, which are then too big to diff use out of the hair. Th e end result achieved results in the balance of these two processes, the mixture of dye precursors, the initial hair color and hair quality.

More complex colors may contain several precursors and many couplers, and involve multiple reactions. To create each shade in the hair coloring spectrum, formulators must become artisans, assessing which developers and couplers to combine, how much

of each to use, and the ratio and total concentration of the various intermediates.

How Coloring Alters Biology

Hair is protected by a covalently bound, mono-molecular layer of unique branched fatty acid — 18 methyl eicosanoic acid (18-MEA). 18-MEA, often referred to as the f-layer, is the fatty lipid layer that binds to the surface of the cuticle and acts as the hair’s natural conditioning system. Because the f-layer has a natural lubricating mechanism and is water repellent, it gives each hair fiber a built-in conditioning system that reduces damage caused by blow-drying and brushing.14, 15

During permanent coloring, the combination of hydrogen peroxide, ammonia and high pH removes some of the protective f-layer, causing additional oxidation of the hair surface and some irreversible physiochemical changes in hair

fi bers. Repeated coloring can cause this protective surface to com-pletely disappear. As a result, the hair becomes hydrophilic (water loving) instead of hydrophobic (water repellent), and the natural lubricating properties are removed. Hair is more susceptible to damage, feels dry and is hard to detangle. It looks duller and less colorful, and requires more conditioning.

Free Radical Formation — EDDS Addresses The HO* Radical

Most hair color users understand that by its nature, permanent color makes irreversible changes to hair structure. Th e bleaching and oxidation action chemically alter hair proteins, lipids and pigments. While pigment changes are desirable, the changes to proteins and lipids can cause hair to be more susceptible to damage. Most consumers adapt to these changes by using conditioners to protect hair and limiting hair color application to once every 4-6 weeks.

However, what they may not know is that not all the damage done by hair colorants is necessary. Th ere are two key reactive species in current permanent hair color: the perhy-droxyl anion (HOO-) and the HO* radical. Th e HOO- species is the species intentionally put in by manufacturers. While it has some damaging side eff ects, it is the

OS

OS

OS

OS

OS

OS

OS

OS

f-Layer of a hair follicle

Outer ß-layer(18-MEA)

d = 2.5 nm

(Jones et al., J. Invest. Dermatol., 106(3), 1996. 461-464)

Epicuticle


species that is responsible for the desired changes to hair color. Th e HO* radical, however, is an undesired by-product of a reaction between H202 and metal ions. It does not con-tribute to the development of color but does contribute to hair damage. Th e elimination of this unnecessary free radical can signifi cantly reduce

hair damage without compromising hair colorant performance. One approach to reducing the free radical is to eliminate the exposure to metal ions. Metal ions come into the hair through exposure to water. Studies show that protein damage, as measured by formation of cysteic acid, is signifi cantly reduced by elimination

of copper in tap water.

Addressing the HO* Radical

Recently, hair color scientists discovered a way to reduce damage from the HO* radical, blocking its formation with the use of chelants — molecules that can coordinate metals through multiple

Performance Data for Chelants vs. the Cu/Ca Conditional Formation Constant Ratio16

Chelant (0.05M) Added to

Colorant Cream

Ratio of Cu to Ca Conditional

Formation Constant

SEM Damage Index Score

F-IR Cysteic Acid Units

No Copper Control – 5.0 100

EDDS 4 x 1011 6.8 110

DTPA 4.6 x 107 49.8 147

EDTA 1.6 x 106 68.6 165

HEDP 7.7 x 103 61.0 163

0 1 2 3 4 5 6 Cycle number

120 –

100 –

80 –

60 –

40 –

20

0

¢ Copper in tap waterNo copper in tap water

FT-I

R c

yste

ic a

cid

un

its

– – – – ––

FT-IR cysteic acid formation in presence vs. absence of copper ions in water

Gas Formation after 10 min., no EDDS

Gas Formation after 10 min., with EDDS

Suppression of Free

Radical Formation

The suppression of free radical formation

can be visualized microscopically by

comparing gas production from a for-

mulation containing no EDDS chelant

(0.1% EDTA) vs. one containing EDDS

(1% level). Signifi cantly fewer gas bubbles

can be seen being formed in the sample

treated with EDDS — clearly demonstrating

the ability of EDDS to reduce the gas

formation signifi cantly.


binding sites. Th ey added EDDS (ethylenediaminedisuccinic acid), a chelant which is highly selective to copper, to home hair coloring kits. During the coloring process, EDDS binds to the copper, preventing access to the copper by hydrogen peroxide, which results in better

color formation and less damage. Th e preference of the EDDS for copper over calcium makes it superior to traditional chelants, such as EDTA or DTPA, and more effi cient at preventing fi ber damage.

A 5-cycle repeat test showed that EDDS prevents more than 95 percent of radical damage. After-care conditioners, which water-proof hair, additionally help prevent damage and copper absorption as color ages. By minimizing free radical damage, advances such as EDDS help hair remain resilient and retain a healthy, lustrous look.17

Old Science vs. New ScienceCarbonate + Glycinate = Hair Fiber Integrity

Exploring the damage caused by current oxidants, it is apparent that an improved option would have numerous benefi ts for preserv-ing hair integrity. Recently, scien-tists made the fi rst new advance in home coloring technology in more than 50 years. By altering coloring chemistry, this breakthrough tech-nology takes hair coloring to a new level, achieving excellent color and shine faster and with less damage to hair. Put simply, it addresses both the key consumer benefi t, good hair color, and the key consumer complaint, hair damage.

Th e technology centers around a new bleach engine, combining ammonium carbonate, hydrogen peroxide and sodium glycinate. Th e result is a powerful oxidative bleach,

NH3

ammonia

H2O2

hydrogenperoxide

HOO-

perhydroxylanion

HO*

hydroxylradical

+

+

+

+

(NH4)2CO3

ammoniumcarbonate

H2O2

hydrogenperoxide

HCO4-

peroxymono-carbonate

C2H5NO2

amino acidsodium glycinate

CO3-*

inactivatedcarbonate

radical

• f-layer removal and significant fiber damage, which affect surface feel

• hydroxyl radical is damagingwithout a radical scavenger

• harsh higher pH

• reduces f-layer and hair fiber damage, leading to improved hair feel

• radical scavenger protects fiber integrity

• gentle lower pH

+

OLD CHEMISTRY NEW CHEMISTRY

pH 10-11

+

pH 9.0

DYE PRECURSORS

BLEACH ENGINE

COLOR FORMATION

BLEACH MELANIN & LIGHTEN HAIR

FIBER DAMAGE

+

+

COLOR FORMATION

BLEACH MELANIN & LIGHTEN HAIR

REDUCED FIBER DAMAGE

+DYE PRECURSORS

BLEACH ENGINE

10 Minutes20–30Minutes


tests demonstrate a high shine with excellent color and gray coverage in ten minutes (compared to the standard 30 minutes), less damage to the f-layer and cuticle, and improved odor.

glycinate acts as a radical scavenger, removing any carbonate radicals being formed, thus minimizing damage to hair.

Together, these elements produce faster, more targeted bleaching and faster color formation with improved hair condition during and after coloring. Technical and consumer

which delivers improved lightening performance with signifi cantly reduced levels of volatile ammonia for a much more beautiful, less chemical, in-use experience.

Th e key bleaching species, the peroxymonocarbonate ion, is formed in situ from the reaction of ammonium carbonate and hydrogen peroxide, and is more selective toward melanin than keratin.

Th e carbonate accelerates bleaching and allows color formation and bleaching to occur at 9.0 pH compared to 10.0 – 11.0 pH, making it less damaging, with ten times fewer basic OH- ions and ten times fewer damaging perhydroxyl anions. Sodium

New Chemistry Benefi ts

Left: Baseline 50% gray, Middle: Ten minutes with new chemistry, Right: Ten minutes with current technology

Left: Hair shaft damages with new chemistry (10 min), Right: Hair shaft damages with current technology (30 min)

O

C-O OH

+ HOOH

O

C-O O OH

Peroxymonocarbonate ion

% f-Layer Retention After One Treatment

TOF SIMS analysis of 18 MEA

1 cycle % f-layer on hair retained

New Chemistry Blonde 34.6

New Chemistry Brown 47.3

Old Chemistry Blonde 0.0

Old Chemistry Brown 2.5

100

90

80

70

60

50

40

30

20

10

0Added Sodium

GlycinateUntreated

HairNo Scavenger

Forc

e to

Bre

ak (

gm

f)

Tensile Strength

treated with ammonium carbonate technology


Hair Color Explored

Factors in Fading Color

Dyes are formulated to give hair long-lasting and richly hued col-ors, but several factors — from mechanical to environmental — can accelerate color changes and fading:

• Poor initial color application. When color has not been given enough time to penetrate the hair shaft, color molecules are not as tightly bound in the cortex, allowing them to be washed away. Most of noticeable fading appears after the fi rst two washes, indicating that the color molecules settled on the outside of the hair shaft and had not penetrated deeply enough to be retained through washes.

• Cuticle damage. Th e cuticle is the primary protection for the hair cortex — where the majority of color molecules are housed. If friction or excessive chemical treatments damage the cuticle and strip away its protective fatty layer, the exposed cortex will chip away, and color molecules will escape during shampooing. Protection of the cuticle with shampoos and con-ditioners that contain friction-reducing silicones helps reduce this type of color loss.

• Water exposure. Fading due to water exposure is often related to a damaged cuticle. When the cuticle is overly compromised, water can more easily enter the cortex and some of the color molecules can be pulled out and washed away. Shampoos do not strip color. In fact, data shows that water alone is responsible for the majority of color lost during shampooing.18 Conditioning shampoos and conditioners with cationic surfactants and waterproofi ng amino silicones can help combat the eff ects of water exposure.

• UV exposure. UV light is known to fade color in many substrates such as wood, cloth and paint. Hair is no diff erent.19 UV

radiation penetrates the hair and breaks down color molecules. Th e process happens with both natural and artifi cial pigments in the cortex — and is the reason people develop highlights after spending long periods of time in the sun. UV protectants are added to some shampoos and styling products to help prevent hair color fade due to sun-light, although their effi cacy is debated. Wearing a hat is the best protection against UV damage.

• Some shades fade more quickly than others. Red shades tend to fade the fastest because they have relatively small molecule size, which can diff use from the hair and wash away more quickly than other shades.20 UV exposure also breaks down the red tone more easily, while pure browns and blacks resist fading because their color molecules tend to be larger. Blonde shades have little color, so fading is less of a concern.

Shine and Color

Human perception of color depends on the ability of our eyes and brains to detect and interpret the refl ection of light on objects. When light shines on hair, part of it penetrates and is absorbed by the dye molecules, and part is refl ected back. Hair’s shine band, which is

Scientists measure shine intensity and chroma saturation in hair color development

Fact vs. Fiction: Hair Dye Revealed

Myth: Coloring is the main cause of hair damage.

Fact: While coloring can be damaging, heat and mechanical damage also

play a signifi cant role.

Myth: All hair colors use the same dyes.

Fact: Many hair colors use the same ingredients, but in unique combinations,

with varying levels and amounts, to create very different colors. Some ingredients

are patented, so they are only used by the original manufacturer. The developers

and couplers can react together to form many different dye molecules, each with

a different color.

Myth: Low ammonia is better for your hair.

Fact: All combinations of ammonia as well as MEA, another alkali, can damage

hair because of their high pH level. The damage, a function of peroxide, occurs

from the chemicals formed when the mixed peroxide and alkali come in contact

with the hair. The primary benefi t of low ammonia is less odor.

Myth: Dyed blonde shades cause more hair damage than brown, red or

black shades.

Fact: The majority of hair shades have similar hair damage profi les. Hair dam-

age is caused by the amount of peroxide and alkali, like ammonia, in the dye.

Most shades use the same amount and concentration of peroxide and have similar

alkali levels.

Myth: Anti-dandruff shampoos cause color to fade faster.

Fact: Successive washing of color-treated hair shows a pyrithione zinc shampoo,

the most effective dandruff treatment to date, to be no different than a cosmetic

shampoo, or even regular tap water.

Myth: Swimming pool water can turn hair green.

Fact: Exposure of blonde hair, particularly chemically bleached or damaged hair,

to high concentrations of copper in tap water or swimming pools can result in

green hair. The best treatment is avoidance; using a bathing cap while keeping

hair healthy and hydrophobic with an aminosilicone-based conditioner. Severe

discoloration may be reversed by a professional stylist, in some cases.


typically around the crown of the head, shows how well the fi bers refl ect light from the surface. Th e chroma band, which lies adjacent to the lighter shine band, is responsible for how successfully color informa-tion is revealed from within hair. Th e stronger the chroma band, the more intense the color will appear. Hair chroma is the colorfulness of hair compared to white. Chroma satura-tion, or color intensity, measures how much color the hair contains. Th e more saturated a color, the more sensation comes from the light of a single wavelength.

Further, damage to the cuticle can diminish hair’s ability to refl ect light, making it appear dull. When developing colors, hair dye formulators seek to mimic hair’s natural shine by developing dye mixtures that penetrate the cuticle in order to maintain color intensity over time, without fading or washing out, but that also help maintain the overall health of hair for maxi-mum shine. Additionally, daily use of shampoos and conditioners containing silicone based ingredients will enhance and refresh hair shine.21

Conditioning Breakthrough

To overcome challenges inherent to the coloring process, scientists have developed a breakthrough technology in the form of a modifi ed silicone that

deposits well on colored hair. Nor-mal silicones are hydrophobic. Th ey attach well to non-colored hydropho-bic hair but not to colored hydrophilic hair, making them wash away easily. Th e modifi ed aminosilicones are more hydrophilic and hence attach much better to colored hair. Th is durable fi lm protects hair from further damage and color fading, preserves color vibrance and shine, and allows hair to regain some of its natural protective water repellence. Technical testing of a conditioner with the modifi ed silicone showed signifi -cantly less fading as a result of washing and exposure to ultraviolet light and reduced damage compared to standard conditioners.

Th e modifi ed silicone functions as part of a patented conditioning gel network base; a releasing active (dialkylquat), and a silicone resin that interact with aminosilicone to provide additional longer-lasting performance to conditioners. Th e key durable active ingredients are amodimethicone, a conditioning agent; dicetyldimonium chloride, a silicone-releasing and conditioning agent; and trimethylsiloxysilicate, a durability aid.

Researchers have also developed a daily maintenance conditioner for colored hair containing a special ingredient, amidopropyl dimeth-ylamine glutamate (BAPDMA),



engineered specifi cally to rebuild the layer. By rebuilding the layer, hair can return to its hydrophobic nature. One side of the BAPDMA molecule attaches to the damaged part of hair. Th e other side mimics the layer, acting as a patch for the damaged areas, and prepares hair for the deposition of silicones. Applied daily, the conditioner provides intensive care for even the most damaged hair, with high levels of condition-ing, moisturizing and protective ingredients that smooth and align hair fi bers for shine and softness.

Hair Color Safety

Hair color products are strictly regulated by government groups in Europe, North America and Japan, and have been proven safe throughout more than a century

of testing and usage by millions of people worldwide. Extensive studies have concluded that hair colorants are safe when used as directed and pose no health risk to pregnant women, unborn babies or infants.

Th e comprehensive scientifi c research portfolio includes studies from the American Cancer Society, Johns Hopkins University School of Public Health, and Cancer Research UK.22 A major review of studies published in the Journal of the American Medical Association in 2005 concluded that there was no increased risk of cancer from the use of hair dyes,23 which confi rmed the results of prior major reviews of more than 70 studies in 1993 by the International Agency for Research on Cancer, a group of the World Health Organization, and 83 studies between 1993 and 2003 by Johns Hopkins University School of Public Health, reviewed by the U.S. Cosmetic Ingredi-ent Review Panel.24 25 In a more recent 2006 update, the U.S. CIR again concluded that the available epidemiology studies are insuffi -cient to conclude there is a casual relationship between hair dye use and cancer (www.cir-safety.org).

Sensitivity Testing

Like other products in common use, such as certain foods or drugs,

hair dyes can cause allergic reac-tions in a few individuals. Aller-gic reactions to hair coloring are very rare, estimated at approxi-mately one in every one million applications, and they mainly occur with very dark hair-coloring shades. However, manufacturers recommend testing the products 48 hours before each salon or home color treatment to determine skin sensitivity, which can change over time. Most hair-coloring pack-ages provide instructions on sen-sitivity testing, which generally advise users to test a small amount of the product on their forearm prior to full application. Some suggest applying a thin fi lm of petroleum jelly around their hairline, but primarily as a safeguard against staining of facial skin rather than as a sensitivity precaution. All hair-coloring products warn against using hair dye on facial hair, such as eyebrows.26

The Bigger PictureFree Radical Formation Across Multiple Disciplines

Free radicals have long been known to damage proteins, oils and other important chemical compounds. Free radicals have been implicated in accelerating aging but also play an important role in degradation

Left: Virgin hair, Middle: Hair colored and treated with new conditioner technology, Right: Hair colored without new conditioner

New Conditioner TechnologyDurable conditioner advances allow for mimicking the hydrophobic layer of virgin hair


of building materials (such as polymers and paints) and degradation of foods. Free radicals are damaging because they attack and damage DNA, proteins (collagen, elastin, keratin) and moisture barrier lipids.Th e primary method for fi ghting free radicals is the use of antioxidants, which slow down the process of aging and the decomposition of cells. Currently the vast majority of anti-aging and UV protection products on the market contain some form of antioxidants. Lifestyle experts from dieticians to personal trainers are toting antioxidant secrets to success. By addressing free radical formation in hair color, researchers are able to further their general knowledge base for other disciplines, promoting overall health benefi ts to consumers.

P&G Research Partnerships

P&G science innovation has been a foundation for company growth and development from the beginning. P&G’s expertise in leveraging cross-discipline connections has allowed a continuous network of people, facilities, technologies and consumers in diff erent regions to create one product from lessons learned from making another. P&G’s laundry care division helped contribute to the discovery of this new chemistry through its own upstream bleach chemistry research

being conducted to help manage radical formation on clothing fi bers, which exemplifi es this continual process of shared ideas and informa-tion throughout the company. Addi-tionally, P&G consistently enlists the collaboration of independent institutes to broaden the scope of research, which in this case include the Textile Research Institute (Princeton, US), DWI (German Wool Research Institute), CSMA (Centre for Surface and Materials Analysis, UK).

What’s Next?Pigmentation Breakthroughs

New understandings in genetics and biology and the role of DNA in dictating the color, condition and health of hair are taking hair-color-ing technology into a whole new realm. By utilizing new technologies, scientists have access to powerful new tools to explore ways to improve hair health and appearance.

For example, research presented at the 2007 Intercontinental Meeting of Hair Research Societies addressed how biochemicals can signifi cantly infl uence hair pigmen-tation. Researchers from Britain and the US studied melanocytes, cells which are responsible for pigment, in hair follicles for the presence of certain hormone receptors that may

aff ect follicle growth and coloration. Th ey found that the hormones may respond diff erently within these and other hair follicle cells, including fi broblasts (responsible for cell struc-ture), depending on their interaction with biochemicals. When the researchers stimulated the melano-cytes with hormone proteins, the reaction induced an increased pro-duction of melanin and cell growth. Th e proteins also stimulated expression and activity of tyrosinase (an important amino acid to melanin production), evoking a conclusion that biochemicals may aff ect specifi c cellular functions when exposed to melanocytes.27

Th ese, and other advances in technology and genetics, prom-ise to improve hair coloring and care in the years ahead, providing women and men in all parts of the world with the tools they need to maintain beautiful, healthy hair.

Hair follicle with melanin granulesCourtesy of Dr. Desmond J. Tobin, University of Bradford, UK

Melanogenic Zone

DP

Dermal sheath

Hair bulb matrix

Summary

New discoveries in hair biology and coloring chemistry have led to signifi cant advances in hair coloring products and possibilities, reducing the trade-off s in hair health.

Researchers have developed new hair coloring technologies that optimize color intensity, minimize the amount of damage in the coloring process, speed processing time, and improve the appearance and health of colored hair. Increased understanding of how hair biology changes during coloring has also allowed formulators to create better tools such as post-coloring conditioners that help improve hair health at a microscopic level to achieve brilliant, long-lasting color and shine.


New research will continue to push the envelope of what is possible in hair color. Moving forward, researchers will continue to build from current breakthroughs, consistently off ering new benefi ts in home hair color. Consumers will not only benefi t from milestones like speed processing time and color intensity, but will be able to indulge in an overall better in-use experience.


1 Bouillon C, Wilkinson J. The Science of Hair Care (Second Edition). CRC Press, 2005; 252-253.

2 Bouillon C, Wilkinson J. The Science of Hair Care (Second Edition). CRC Press, 2005; 252-253.

3 Draelos ZD. Hair Care — An Illustrated Dermatologic Handbook. UK, Taylor & Francis, 2005; 85.

4 Data on fi le, P&G Beauty




8 Robbins C. Chemical and Physical Behavior of Human Hair, 4th ed. Springer-Verlag NY, 2002; 4.

9 Draelos ZD. Hair Care — An Illustrated Dermatologic Handbook. UK, Taylor & Francis, 2005; 95.

10 Olsen E. Disorders of Hair Growth. McGraw Hill, NY, 1194; 54.

11 Slominsk A, Wortsman J, Przemyslaw MP, Schallreuter K, Paus R, Tobin D. Hair Follicle Pigmentation, Journal of Investigative Dermatology (2005) 124, 13–21.

12 Gray J. The World of Hair Colour. Thomson Learning, London, 2005; 62-89.

13 Draelos ZD. Hair Care — An Illustrated Dermatologic Handbook. UK, Taylor & Francis, 2005, 94.

14 Carr MC, Holt LA, Drennan J. Using electron microscopy and X-ray microanalysis to study wool morphology and composition. Text Res J 1986, 56: 669-673.

15 Marsh J, Gummer C, Dahlgren M. Novel Permanent Hair Coloring Systems Delivering Color with Reduced Fiber Damage, Journal of Cosmetic Science, Vol. 58, No. 1, January / February, 2007.

16 Negri AP, Cornell HJ, Rivett DE. A model for the surface of keratin fi bres. Text Res J 1993, 63: 109-115.

17 Boswell et al, The Procter & Gamble Company. Composition suitable for the treatment of hair comprising chelants and methods for reducing oxidative hair damage. US Patent 7186275. Sep. 22, 2003.

18 Schwartz J. A Practical Guide to the Occurrence and Treatment of Dandruff and Seborrheic Dermatitis. Presented at the 62nd annual meeting of the American Academy of Dermatology, Washington DC, Feb. 6-11, 2004.

19 Bouillon C, Wilkinson J. The Science of Hair Care, (Second Edition). CRC press, Boca Raton, 2005, 247.

20 Bouillon C, Wilkinson J. The Science of Hair Care (Second Edition). CRC press, Boca Raton, 2005, 435.

21 Draelos ZD. Hair Care — An Illustrated Dermatologic Handbook. UK, Taylor & Francis 2005, 40.

22 The European Cosmetic Toiletry & Perfumery Association Ltd. (COLPA), London. Statement, Aug. 16, 2005.

23 Takkouche B, Etminan M, Montes-Martinez A. Personal Use of Hair Dyes and Risk of Cancer: A Meta-analysis. JAMA 2005, 293: 2516-2525.

24 International Agency for Research on Cancer (IARC). Occupational exposures of hairdressers and barbers and personal use of hair colourants, some hair dyes, cosmetic colourants, industrial dyestuffs and aromatic amines. IARC Monographs on the evalutation of carcionogenic risks to humans 1993; Vol 57: 43 – 118.

25 Helzlsouer K, Rollison D, Pinney S. Association between hair dye use and health outcomes: Review of the literature published since 1992. Unpublished data submitted by Clairol, Inc. to the US CIR, 2003.

26 Draelos ZD. Hair Care — An Illustrated Dermatologic Handbook. UK, Taylor & Francis 2005, 113-114.

27 Kauser S, Slominski A, Wei T, Tobin D. Modulation of the Human Hair Follicle Pigmentary Unit by Corticotropin-Releasing Hormone and Urocortin Peptides. Presented at the 2007 Intercontinental Meeting of Hair Research Societies.

references

AN ADDITIONAL TOOL

The Hair Color: Research Update CD holds a PowerPoint presentation of the charts and illustrations in this toolkit. Feel free to use the images. Please credit P&G Beauty.

CONTACT INFORMATION

To talk with a P&G scientist or to learn more about ongoing research in the Beauty Science division, visit pgbeautyscience.com, or contact:

Dianna KenneallyP&G Beauty Science513-626-3508

Heather CunninghamP&G Beauty Science513-626-2606

p&g research update hair color

Documents