Hair dye

Hair dye

Hair dye cosmetics have the effect of changing the color of the hair, commonly known as hair dyes. The Chinese belong to the yellow race, and most of them take white hair to dye black for their beauty, so the hair dye is relatively monotonous. Europeans and Americans are accustomed to bleaching or bleaching their hair first, and then dye their hair into golden, yellow, flax, reddish brown, violet, etc., so there are many varieties of hair dyes.

Temporary hair dye is a hair dye that only needs to wash with shampoo once to remove the color on the hair. Due to the large particles of these hair dyes, they cannot enter the hair shaft through the epidermis, but are deposited on the surface of the hair to form a colored covering layer. In this way, the interaction between the dye and the hair is not strong, and it is easy to be washed away by shampoo.

Semi-permanent hair dye generally means that it can withstand 6-12 times of shampoo washing before fading. Semi-permanent hair dye is applied to the hair and left for 20-30 minutes, rinsed with water to make the hair color. Its working principle is that dye molecules with relatively small molecular weight penetrate into the epidermis of the hair, and part of it enters the cortex, making it more resistant to shampoo cleaning than temporary hair dyes. Because it does not need to use hydrogen peroxide and will not damage the hair, it has become more popular in recent years.

There are three types of permanent hair dyes: plant permanent, metal permanent, and oxidation permanent.

1. Plant permanence:

It is expensive to dye with substances extracted from the stems and leaves of plants.

2. Metal permanence:

Dyeing with metal raw materials, the dyeing is mainly deposited on the surface of the hair shaft, and the color has a darker metallic appearance, which makes the hair brittle and the efficiency of perming is low.

3. Permanent oxidation:

The mainstream products on the market do not contain dyes in general, but contain dye intermediates and coupling agents. After these dye intermediates and coupling agents penetrate into the cortex of the hair, they undergo oxidation, coupling and condensation reactions to form larger The dye molecules are enclosed in the hair fiber. Due to the different types and content ratios of dye intermediates and coupling agents, reaction products with different shades are produced, and the various shade products are combined into different shades to dye the hair with different colors. Because the dye macromolecule is generated in the hair fiber through the reaction of the dye intermediate and the small molecule of the coupling agent. Therefore, during washing, the formed dye macromolecules are not easily washed through the pores of the hair fiber.