Chemical depilatory

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.

Presently, these skin depilatory are also available in the powder form to remove hairs as hair shaving powder. They help protect skin bump-offs in the facial skin of the black men which occur during regular shaving with a razor blade in black men. The shaving powder contains sodium carbonate as the base besides corn starch as the binder and vitamin E and jojoba oil. The concentration of CaTG is rather high in a CATG based shaving powder leading to hair removal from the shaving area in 7-9 min. The depilatory hair remving cream usually take about 15-20 min as they contain low CaTGH.

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

Advantages

 * Inexpensive
 * Fast
 * Various strength products available to dissolve even the strongest of hairs
 * Can be done at home
 * Available over-the-counter

Disadvantages

 * Effect lasts a short time. Regrowth appears generally within 2-5 days.
 * Dark-haired users may be left with a visible "shadow" of dark hair under skin.
 * Chemical depilatory creams are generally foul in odor and messy to use.
 * Can cause severe skin irritation or allergic reactions.