Hair coloring is the practice of changing the color of hair. Common reasons are to cover gray hair, to change to a color regarded as more fashionable or desirable, and to restore the original hair color after it has been discolored by hairdressing processes or sun bleaching.
Hair coloring is very popular today, with over 75% of women coloring their hair and a growing percentage of men following suit.
The first safe commercial haircolor was created in 1909 by French chemist Eugene Schuller, using the chemical paraphenylenediamine.
What is hair:
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 phaeomelanin. Eumelanin is responsible for brown to black hair shades while phaeomelanin is responsible for golden blond, ginger, and red colors. The absence of either type of melanin produces white/gray hair.
HOW COLORANT PREPARED ?
The most popular way to achieve permanent hair coloring is through the use of oxidation dyes. The ingredients include 1,4-diaminobenzene (historically) or 2,5-diaminotoluene (currently), a coupling agent, and an oxidant. The process is typically performed under basic conditions.
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How does haircolor work?
It's the result of a series of chemical reactions between the molecules in hair, pigments, as well as peroxide and ammonia, if present.
Hair colorants
haircolors may deposit acidic dyes onto the outside of the hair shaft or may 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 colorant molecules enter the hair to form a larger complex inside the hair shaft. Shampooing will eventually dislodge temporary hair color. These products don't contain ammonia, meaning the hair shaft isn't opened up during processing and the hair's natural color is retained once the product washes out.
Natural Colorants
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) and others contain natural bleaching agents or cause reactions that change the color of hair (e.g., vinegar). Natural pigments generally work by coating the hair shaft with color. Some natural colorants last through several shampoos, but they aren't necessarily safer or more gentle than modern formulations. It's difficult to get consistent results using natural colorants, plus some people are allergic to the ingredients.
