설명(영) |
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Hair Colorants are materials which impart color to hair. Hair coloring preparations may be classified as temporary, semi-permanent, permanent, or progressive, according to the length of time the colorant remains on the hair.
Temporary coloring preparations, often called color rinses, provide color which lasts until the first shampooing. Ingredients which impart temporary color may have a fairly high molecular weight and are unable to penetrate the hair shaft. These materials are simply deposited onto the hair fiber and are removed by subsequent shampooing.
Semi-permanent coloring preparations generally provide color through several shampooings. These materials are often low molecular weight pre-formed dyes which can penetrate the hair shaft to some extent.
Permanent hair coloring preparations provide color that is not removed by shampooing. The reactions required for permanent hair dyeing are oxidation reactions, and these colorants are often referred to as oxidation dyes. Permanent coloration involves the deposition of an essentially colorless intermediate and of a coupling agent inside the hair fiber. In the presence of an oxidizing agent, usually hydrogen peroxide, these chemicals form a series of complex dyestuffs inside the hair fiber.
Progressive hair coloring preparations are permanent hair colors which develop color gradually by repeated applications. |