{{short description|Cosmetic preparation used to remove hair from the skin}} A '''chemical depilatory''' is a cosmetic preparation used to remove hair from the skin. Common active ingredients are salts of thioglycolic acid and thiolactic acids. These compounds break the disulfide bonds in keratin and also hydrolyze the hair so that it is easily removed. Formerly, sulfides such as strontium sulfide were used, but due to their unpleasant odor, they have been replaced by thiols.<ref>{{citation | contribution=Hair Preparations | title=Ullmann's Encyclopedia of Industrial Chemistry | edition=7th | year=2007 | doi=10.1002/14356007.a12_571.pub2}}</ref>

The main chemical reaction affected by the thioglycolate is: : {{nowrap|2 HSCH<sub>2</sub>CO<sub>2</sub>H (thioglycolic acid) +}} {{nowrap|R-S-S-R (cystine) →}} {{nowrap|HO<sub>2</sub>CCH<sub>2</sub>-S-S-CH<sub>2</sub>CO<sub>2</sub>H (dithiodiglycolic acid) +}} {{nowrap|2 RSH (cysteine)}}

Chemical depilatories contain 5–6% calcium thioglycolate in a cream base (to avoid runoff). Calcium hydroxide or strontium hydroxide maintain a pH of about 12. Hair destruction requires about 10 minutes. Depilation is followed by careful rinsing with water, and various conditioners are applied to restore the skin's pH to normal. Depilation does not destroy the dermal papilla, and the hair grows back.<ref>{{citation | editor=Arza Seidel|display-editors=et al | title=Kirk-Othmer Chemical Technology of Cosmetics | year=2013 | page=44}}</ref>

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

Chemical depilatories are indicated in the treatment of hirsutism in polyendocrine metabolic ovarian syndrome.

Depilatory ointments, or plasters, were known to Greek and Roman authors as ''psilothrum''.<ref>{{citation | entry=PSILOTHRUM | title=Dictionary of Greek and Roman Antiquities | edition=3rd | year=1890}}</ref> In Jewish lore, King Solomon is said to have discovered a chemical depilatory made from a mixture of lime and water and orpiment (arsenic trisulfide).<ref>Colloquy of the Queen of Sheba, taken from the Aramaic ''Targum Sheni of Megillat Esther''.</ref>

==References== {{reflist}}

{{Cosmetics}} {{Human hair}}

{{DEFAULTSORT:Chemical Depilatory}} Category:Hair removal