ABSTRACT
Consumer hair dye products can be divided into three product types; permanent, semi-permanent, and temporary. Permanent or oxidation hair colors are the most widely used hair dye products. Oxidation hair dye products contain a solution of dye intermediates which form hair dyes by chemical reactions on the hair, and preformed dyes that are added as toning agents to attain the intended shades. The dye solution and the hydrogen peroxide solution (developer) are mixed just prior to hair application. The applied mixture causes the hair shaft to swell. The dye intermediates (and toning dyes) penetrate the hair shaft to some degree before they have chemically reacted with the hydrogen peroxide to form the final colored hair dye. Semipermanent and temporary hair coloring products are typically solutions of several hair dyes, which bind to the hair shaft to differing degrees. Temporary hair colors need to be reapplied after each shampooing.
