The majority of cosmetic formulation are designed to improve biological surfaces through some physical interaction. For example, shampoos help physically remove oil and dirt from hair; makeups physically change the color of skin. While these products significantly modify the appearance of their targeted sufaces, the effects are temporary because they do not chemically modify the surface.
There are, however, a few cosmetic product types that rely on chemical reactions with the biolocal surfaces to create more "permanent" effects. In hair care, these types include dyes, perms and relaxers. In skin care, the most common type is sunless tanners.
Excerpt Only This is a shortened version or summary of the article that appeared in the Sep. 1, 2001 issue of Cosmetics & Toiletries magazine. The full content is not currently available online.