Dandruff
A condition of shedding dead cells of the scalp. Usually caused by sebhorric dermatitis.
Dicaprate
Emulsifier.
Dicaprylate
Emulsifier.
D&C
A prefix designating that a certifiable color has been approved for use in drugs and cosmetics.
D&C Red No. 7 Calcium Lake
Synthetic organic colors derived from coal and petroleum sources (not permitted for use around the eye).
Deep Penetrating Treatment
A conditioner for hair meant for occasional use. Of greater intensity than ordinary conditioners. Formulas usually contain protein, vitamins, and moisture to help dry, damaged hair.
Deodorant
A product used to counteract odors caused by the decomposition of sweat on the body. Contain antiseptic substances to kill bacteria and strong fragrances to mask offensive smell. (Not to be confused with antiperspirants which actually inhibit production of sweat.)
Depilatory
Product used to remove hair from the follicle.
Diazolidnyl
Preservative.
Dimethicone
Moisturizing silicone skin and hair conditioner and anti-foam ingredient.

Dimethicone Copolyol
Complex of natural silica, acts as a spreading agent for easy application of product; also functions as a moisturizer.
DMDM hydantoin
Preservative, antimicrobial to fight bacteria.
Double Process
A color service which requires two steps to complete. First the hair is lightened and second the new color is added.
Draize test
An animal test used to determine the effects of different substances on the eye.