Depilatories

A chemical depilatory is a cosmetic preparation used to remove the hair from the skin on the human body. Currently, a common active ingredient is calcium thioglycolate, which breaks down the disulfide bonds in keratin and weakens the hair so that it is easily scraped off where it emerges from the hair follicle.

This break down reaction is affected by the calcium hydroxide (an alkali). The resulting combination of calcium hydroxide and thioglycolic acid is calcium thioglycolate(CaTG). The calcium hydroxide is present in excess to enable the thioglycolic acid to react with the cystine present in hair protein. The reaction is 2SH-CH2-COOH(thioglycolic acid) +R-S-S-R(cystine)-----> 2R-SH + COOH CH2 SS CH2 COOH (dithiodiglycolic acid).

As the epidermis is also rich in keratin, the skin may become irritated and sensitive if the preparation is left on for too long. Chemical depilatories are used primarily for the arms and legs. They should not be used on the face unless specifically listed for that purpose on the product's label.

Chemical depilatories are available in gel, cream, lotion, aerosol, roll-on, and powder forms. Common brands include Nair, Magic Shave and Veet.