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About Hair Color

The first safe commercial hair color was created in 1909 by French chemist Eugene Schuller, using the chemical paraphenylenediamine. Hair coloring is very popular today, with over 85% of women coloring their hair and a growing percentage of men following suit.

How Does Hair Color Work ?

Hair is mainly keratin, the same protein found in skin and fingernails. The natural color of hair depends on the ratio and quantities of two other proteins, eumelanin and pheomelanin. Eumelanin is responsible for brown to black hair shades while pheomelanin is responsible for golden blond, ginger, and red colors. The absence of either type of melanin produces white/gray hair.

Hair Lightening

Hydrogen peroxide is one of the most common lightening agents. The peroxide is used in an alkaline solution, which opens the hair shaft to allow the peroxide to react with the melanin. The Lightener reacts with the melanin in hair, removing the color in an irreversible chemical reaction. The Lightener oxidizes the melanin molecule. The melanin is still present while the oxidized molecule is colorless. Lightened hair tends to have a pale yellow tint, which is the natural color of keratin (the structural protein in hair). Lightener reacts more readily with the dark eumelanin pigment compared to pheomelanin, leaving some red or gold residual color after lightening.

Temporary Hair Color

Temporary or semi-permanent hair colors deposit acidic dyes onto the outside of the hair shaft and consist of small pigment molecules that can slip inside the hair shaft, using a small amount of peroxide or none at all. In some cases, a collection of several color molecules enter the hair to form a larger complex inside the hair shaft. Shampooing will eventually remove temporary hair color. Temporary hair colors do not contain ammonia, meaning the hair shaft is not opened up during processing and the natural hair color is retained once the product washes out.

Permanent Hair Color

The outer layer of the hair shaft, the cuticle, must be opened before permanent color can be deposited into the hair. Once the cuticle is opened, the dye reacts with the inner portion of the hair, the cortex, to deposit or remove the color. Most permanent hair colors use a two-step process (usually occurring simultaneously) which first removes the original color of the hair and then deposits a new color. This is essentially the same process as lightening, except a color is then bonded within the hair shaft. Ammonia is the alkaline chemical that opens the cuticle and allows the hair color to penetrate the cortex of the hair. It also acts as a catalyst when the permanent hair color comes together with the peroxide. Peroxide is used as the developer or oxidizing agent. The developer removes pre-existing color. Peroxide breaks chemical bonds in hair, releasing sulfur, which accounts for the characteristic odor of hair color. As the melanin is de-colorized a new permanent color is bonded to the hair cortex. Various types of alcohols and conditioners may also be present in hair color. The conditioners close the cuticle after coloring in order to seal in and protect the new color.

Natural Color

People have been coloring their hair for thousands of years using plants and minerals. Some of these natural agents contain pigments (e.g., henna, black walnut shells) while others contain natural bleaching agents which cause reactions that change the color of hair (e.g., vinegar). Natural pigments generally work by coating the hair shaft with color. Some natural colors last through several shampoos. Natural colors are not necessarily safer or gentler than modern formulations. It is difficult to get consistent results using natural colorants.  Finally, some people are allergic to the ingredients in the natural dyes.