Hair Dye

In the United States, the percentage of women who color their hair grew from about 7 percent in 1950 to more than 75 percent in 2001.

Hair dye is a product that changes the color or tone of hair. Each year, hair coloring products account for $7 billion of the $37 billion hair-care industry earnings worldwide. Sales in the United States make up over $1 billion of these earnings. The percentage of American women who color their hair grew from about 7 percent in 1950 to more than 75 percent in 2001. This proportion is expected to increase as the baby boomers (people born between 1946 to 1964) turn gray. In addition, more and more men are coloring their hair, representing more than $113 million in home-use sales in 2001. Manufacturers are also attracting the younger population, especially teenagers who are using hair color as a fashion accessory.

Early hair dyes

People have used hair dyes since ancient times. Records of ancient Egyptians, Greeks, Hebrews, Persians, Chinese, and early Hindus mention the use of hair coloring. The ancient Egyptians did not care for gray hair and developed different methods to cover it. The orange-red dye obtained from the leaves of the henna shrub was a popular hair coloring rinse. Both men and women experimented with different colors, including blue, green, gold, and red. Mummies have even been found with dyed hair.

Ancient Persians also used henna to color not only their hair and beards but also their faces. Ancient Greek women dyed their hair blue and sprinkled it with colored powder, while the men dyed theirs red to show courage. Ancient Romans used the mineral calcium oxide, or quicklime, to achieve a red-gold hair color. To change gray hair to a dark brown color, they used walnut oil made from walnut shells soaked in olive oil.

Before the invention of modern dyes, Europeans and Asians used different plant extracts for hair dyes. Indigo, a fabric dye, was combined with henna to produce light brown to black shades. An extract of chamomile flowers used to lighten hair color is still used in many hair preparations today. Hair dye was also obtained from the wood of some trees—brown dye from the brazilwood tree and yellow dye from the fustic, a tree in the mulberry family. Some of these plant-derived dyes were mixed with metal, such as copper and iron, to produce longer lasting or richer shades.

Metallic salts, powders, and crayons

During the Renaissance (fourteenth through sixteenth centuries), Italian women produced the popular golden red coloring by combing a solution of rock alum, black sulfur, and honey through their hair and then drying it in sunlight until they had achieved the desired shade. Other hair dyes dating back to the sixteenth century included preparations of lead, quicklime, and salt, or silver nitrate and rose water.

During the seventeenth and eighteenth centuries in Europe, pure white powder for hair or wigs was a sign of aristocracy. White powder was made of wheat starch or potato starch, sometimes mixed with plaster of Paris, flour, chalk, or burnt alabaster (a white mineral used for agriculture). Powdered wigs were especially popular among men.

Some experimented with colored powders, made by adding natural pigments to white powder. For example, to make brown powder, burnt sienna or umber, each a type of soil containing iron or manganese oxide, was mixed with white powder. A black ink called India ink was used to make black powder. Some people bleached their hair with lye, which made it fall out.

Other hair colorants were made from wax, soap, and pigments formed into crayon-like blocks. The block was dampened and rubbed on the hair, or applied with a wet brush. These natural substances remained the sources of hair dyes until the nineteenth century. During the mid-nineteenth century, powdered gold and silver became a fad. This was a throwback to biblical times, when people used powdered gold on their hair.

Modern hair dyes

French chemist Louis-Jacques Thenard (1777–1857) discovered hydrogen peroxide, a compound of hydrogen and oxygen, in 1818, but it was not until 1867 that its use as a hair lightener was recognized. During the 1880s, the amino dyes were developed and marketed in Europe. In 1907, French chemist Eugene Schueller (1881–1957) created the first safe commercial hair color formula, which he called Auréole. The formula, based on a new chemical, paraphenylenediamine, led to the foundation of the French Harmless Hair Dye Company, now popularly known as L'Oréal.

The 1950s saw the growing popularity of home-use hair coloring products. The introduction of semipermanent colors further spurred their sales. In the 1980s, the demipermanent products were introduced. They lasted longer than semipermanent colors.

So many choices

Hair dye products come in three basic categories—Level 1 (semipermanent color), Level 2 (demipermanent color), and Level 3 (permanent color). A semipermanent dye does not lighten the hair because it does not contain peroxide or ammonia. It does not interact with the hair's natural pigment and imparts color by coating the hair. It covers just 50 percent of gray hair and generally lasts about six to twelve shampoos. A demipermanent dye does not contain ammonia so it does not lighten the hair. However, it contains a small quantity of peroxide and lasts about twenty-four to twenty-six shampoos.

Permanent hair dyes are the most popular of the three basic types of hair dyes because the color lasts until the person's natural hair color begins to grow in. They work by lightening the hair's melanin, or natural pigment, and then coloring it. There are two types of permanent hair dyes—the oxidation hair dye and the progressive hair dye. Oxidation hair dye products contain a solution of hydrogen peroxide (the developer) and an ammonia solution of dye intermediaries and preformed dyes (the couplers). The dye intermediaries undergo a chemical reaction to form color, while the preformed dyes aid in achieving the desired shade. The second type of permanent dye is the progressive hair dye, which is typically used by men. Progressive hair dyes are applied over a period of time and change hair color gradually. Lead acetate, a color additive, is generally the active ingredient used in these hair dyes. Although the U.S Food and Drug Administration (FDA) has approved lead acetate (0.6 percent concentration) for progressive hair dyes, there are questions about its absorption into the body. To play it safe, many men have switched to women's hair dyes for color changes.

Raw Materials

Most commercial hair dye formulas are complex, produced from dozens of ingredients. Moreover, the formulas differ from manufacturer to manufacturer. Hair dyes are generally made from dyes, modifiers, antioxidants, alkalizers, soaps, ammonia, wetting agents, and fragrance.

Hair dyes also contain small amounts of chemicals that give hair a certain characteristic (such as a softer texture) or give a desired action to the dye (such as making it more or less permanent). The chemicals used are usually amino compounds and are listed on the product ingredient list with such names as 4-amino-2-hydroxytoluene and m-Aminophenol. Metal oxides that are used as pigments include titanium dioxide and iron oxide.

Modifiers are chemicals that stabilize the dye pigments or modify (make slight changes to) the shade. Modifiers may bring out a color tone, such as green or purple, which complements the dye pigment. Resorcinol is a commonly used modifier. Antioxidants prevent the dye from reacting with the oxygen in air. Sodium sulfite is the antioxidant most commonly used. Alkalizers are added to change the pH (acidity) of the dye formula because the dyes work best in a highly alkaline formula. The alkalizer ammonium hydroxide is commonly used.

In addition to the basic ingredients above, a manufacturer may add other substances to the formula to give the product characteristics that distinguish it from other products in the market. These include fragrances and shampoos, as well as ingredients that make the product foamy, creamy, or thick.

HAIR DYE KNOW-HOW

•The same permanent hair dye may produce different results in different users. This is because the product works with the hair's natural pigment, called melanin, as the color base. Before permanent color can be applied on the hair, hydrogen peroxide has to first break the melanin down to an almost colorless liquid that then drips out of the hair. Only after the person's natural hair color has been removed can the dye work on the hair. The resulting color is, therefore, a combination of the lightened natural pigment and the added dye color.

•Hair color instructions tell consumers that hair color should be applied to clean "unshampooed" hair. Applying hair color right after shampooing can increase the sensitivity of the scalp, because shampooing removes or reduces the natural oils that protect the scalp during the coloring process. The natural oils in hair also help color to cling to strands.

Demipermanent and permanent hair dyes are typically packaged with a developer, which is in a separate bottle. The developer generally has a hydrogen peroxide base, with small amounts of other chemicals. The developer starts the chemical process that brings out the color of the hair dye. It also allows the hair color to last longer.

The Manufacturing Process

Although the formulas for hair dye may differ from manufacturer to manufacturer, the basic production steps are similar.

Checking the ingredients

1 Before a batch of hair dye is made, the chemicals are tested to ensure they are what they are labeled and they are of the correct strength. This process is called certification and may be performed by the manufacturer in-house. In many cases, the ingredients arrive with a Certificate of Analysis from a reputable distributor, and this certification satisfies the manufacturer's requirements.

Weighing

2 A worker weighs out the ingredients for a batch. If several ingredients are needed in large amounts, they may be piped in from storage tanks.

Premixing

3 For some hair dye formulas, the dye chemicals are premixed in hot water. The dyes are put in a tank and hot water (158 degrees Fahrenheit or 70 degrees Celsius) is piped in. Other ingredients may also be added to the premix, which is stirred for about twenty minutes.

Mixing

4 Next, the premix is added to a larger tank that contains the rest of the ingredients. If a small batch is being prepared, the portable (movable) tanks used may hold about 1,600 pounds (725 kilograms) of ingredients. A worker wheels the premix tank to the second tank and pours the ingredients. If a large batch is being prepared, the tanks may hold ten times as much as the portable tanks. In this case, the two tanks are connected by pipes. For hair dye formulas that require no premixing, the ingredients are mixed in a tank until the proper consistency is reached.

In some cases, certain ingredients in the second mix are not added during the mixing process. After the hot premix and most of the other ingredients are blended in the second tank, the resulting mixture is allowed to cool. For example, alcohol is not added until the combined mixture is cooled down to 104 degrees Fahrenheit (40 degrees Celsius) because it tends to evaporate at a higher temperature. Fragrances are also added at the end of the mixing process.

Filling

5 The finished batch of hair dye is delivered or piped to a tank with a nozzle in the filling area. Bottles moving on a conveyor belt are filled with measured amounts of the hair dye. The bottles then move on to machines that seal them with caps and affix labels.

Packaging

6 From the filling area, the bottles are taken to the packaging line. The hair dye bottle is put in a box. Other items are added to the box, including a developer, special finishing shampoo, instruction sheet, gloves, and cap. Completed packages are put into shipping cartons, which are taken to the warehouse for distribution.

Quality Control

Although the FDA controls what ingredients may be used in hair dyes, it does not have the authority to require manufacturers to test their products. The FDA is also not authorized to review the results of company testing. Only after consumers have complained about a certain product does the FDA decide if it needs to investigate. The FDA determines if other complaints have been made or if the product has caused serious reactions. If enough evidence shows that the product is harmful, the FDA requests the manufacturer to pull the product from the market.

Reputable manufacturers make sure their researchers test a hair dye formula many times in the laboratory before it reaches the manufacturing stage. They conduct experiments to ensure, among other things, that a formula is non-irritating, works well, and produces the same result each time.

As part of the manufacturing process, workers check their chemicals before they are put into a batch to make sure the correct chemicals with the correct strength are used. After the batch is mixed, samples are taken and subjected to a series of standard tests. Laboratory technicians check the batch for the required viscosity (resistance to flow) and pH (acidity) balance. They also test the batch on a swatch of hair. If the formula is new or if it has been altered, technicians will also test samples of the dye after the filling stage.

The Future

Hair dye manufacturers are increasingly using computers to control and automate the manufacturing process. Computers are used to weigh and measure ingredients, to control chemical reactions, and to regulate equipment, such as pumps. The future may see greater production efficiency as hair dye production becomes fully automated.

CONSUMER SMARTS

The U.S. Food and Drug Administration (FDA) encourages consumers to report any adverse reaction they have experienced in using certain hair coloring products. These products are not subject to government review prior to marketing; therefore, the general public only hears about problems with a product if consumers bring their complaints to the government's attention. For information on how to report adverse reactions to hair dyes and other cosmetics, as well as problems such as filth, decomposition, or spoilage, the consumer may call FDA's Office of Cosmetics and Colors at 1-202-401-9725. Complaints may also be sent in writing to: FDA, Office of Cosmetics and Colors (HFS-100), 200 C St., SW, Washington, DC 20204.

In the meantime, manufacturers who test their products continue to do so without having to follow government testing standards. Moreover, the FDA does not see any change in government regulation of hair dyes in the future. As long as manufacturers label their products with such warnings as the possibility of the hair dye causing allergic reactions, they are safe from legal action. Some scientists are conducting research on the possible link of prolonged use of hair dye to the incidence of cancer, and the FDA claims that it is following these studies.

antioxidant:

A substance that prevents the hair dye from reacting with the oxygen in the air.

demipermanent hair dye:

Does not contain ammonia so it does not lighten the hair. However, it contains a small quantity of peroxide and lasts about twenty-four to twenty-six shampoos.

melanin:

The natural pigment of the hair.

permanent hair dye:

Works by lightening the hair's melanin, or natural pigment, and then coloring it.

pH:

A measure of the acidity of a liquid or solution.

pigment:

A natural substance occurring in, and giving color to, a plant or animal.

semipermanent hair dye:

Does not lighten the hair because it does not contain peroxide or ammonia. Imparts color by coating the hair. It generally lasts about six to twelve shampoos.

For More Information

Periodicals

Gorman, Jessica. "Chemistry of Color and Curls." Science News. (August 25, 2001): pp. 124–126.

Krueger, Diane. "Countdown to Color." SalonNews. (September 2001): pp.66–68.

McCann, Lauren. "To Dye for Hair." Teen Magazine. (May 2001): pp.89–97.

Meadows, Michelle. "Are Hair Chemicals Safe for You?" Consumers' Research Magazine. (March 2001): pp. 19–21.

Web Sites

Cormeny, Sara. "Color-Coded Hair." Public Broadcasting Service.http://www.pbs.org/newshour/infocus/fashion/hair.html (accessed on July 22, 2002).

"How Hair Coloring Works." Marshall Brain's HowStuffWorks.http:www.howstuffworks.com/hair-coloring.htm (accessed on July 22, 2002).

Raber, Linda. "What's that Stuff?" Chemical & Engineering News: The Newsmagazine of the Chemical World Online.http://pubs.acs.org/cen/whatstuff/stuff/7811scit4.html (accessed on July 22, 2002).