1. Epidermal layer: It is composed of fish-scale thin transparent body with 27-28 layers. Mainly composed of hair scales, it controls the smoothness and hardness of hair. When the hair scales are tightly wrapped, the hair is hard, and when it is loosely wrapped, the hair is soft. If scales grow in the same direction, hair will be straight. If the hair scales grow in different directions, the hair will appear irregular bending and short-tempered.
2. Cortical layer: It is composed of spiral protein fibers and contains melanin particles inside. The middle layer of hair tissue structure is mainly composed of collagen and some water. Hair quality damage is mainly caused by the loss of collagen and water after the hair scales are opened, which leads to dry and split hair.
3. Medullary layer: It is made of vacuum sponges. Don't use the innermost layer of hair when perming. After some investigation, due to modern air pollution and the application of a large number of chemicals, the pith layer has gradually separated from the internal structure of our hair.
Four keys to hair:
1. disulfide bond: the strongest bond among the four bonds, and only thioglycolic acid in the drug can be cut off. Is to control the size of the coil. It can be cut to different degrees according to the hair quality and curl.
2. Salt bond: With the damage of hair and the increase of alkalinity, the salt bond will also soften, which will also cause some wrong impressions and misjudgments when we soften this kind of hair.
3. Amino bond: a channel for transporting nutrients, making hair thick and soft, and controlling the thickness of hair diameter. Most westerners' hair has no amino bond, so it is thin and soft, while most orientals' hair has amino bond, so it is thick and hard.
(4) Hydrogen bond: it will break when it meets water, and it will also break when it meets high temperature. Heating to 135 degrees produces memory. Control the elasticity of hair curl. This is also a key to distinguish between cold perm and hot perm.
Extended data:
The three layers and four keys of hair is a theory that hairdressers must know. Using the physical and chemical properties of hair, the ammonia in the reducing agent expands to make the hair scales open, so that other chemical components can enter, and the hair scales are rolled into the desired flower shape with tools such as curling irons, and then curled and shaped by the action of oxidants to achieve the effect of cold perm.
Melanin contained in cells is the key to determine the color of hair. China people's hair is black, because there is more melanin. On the contrary, Europeans and Americans have brown hair because there is less melanin in hair. Its task is to protect the head from direct sunlight.
References:
Hair-Baidu Encyclopedia