1 Epidermal layer: Epidermal layer is the outermost layer of hair, consisting of multiple layers of overlapping keratin sheets, and its outer edge is beyond the starting point.

2 Cortical layer: Cortical layer is the second layer of hair, which is the middle layer. It is a bundle of fiber cells surrounded by paste, which contains keratin such as ammonia bond, hydrogen bond, salt bond and disulfide bond, as well as natural pigment particles of hair. The hair stylist should study the bleaching and dyeing in the cortex, and the permanent color is formed by the change of the cortex. Cortical layer accounts for 80% of hair.

3 Medullary layer: In the center of the hair is the medullary layer, which is composed of transparent polygonal cells separated from each other and does not need to be studied in hair dyeing.

Second, the role of hair dye

There are basically three kinds of hair dyes: temporary hair dyes, semi-permanent hair dyes and permanent hair dyes.

1 temporary dye: this is a water-soluble dye and will not enter the hair. It is temporarily attached to the hair surface and will fall off when washed.

Semi-permanent dye: the first-class hair color does not need to add any oxidant. When it penetrates into the cortex, oxidative polymerization does not occur. Generally keep 15 days.

Permanent dyes: Almost all permanent dyes are oxidized and infiltrated by aniline. These dyes penetrate into the epidermis of hair and enter the cortex. This kind of dye must be added with H2O2 (dioxygen emulsion), so it is also called oxidation dye. It usually lasts for 3 months.

Permanent dyes are usually used

1 100% covers white hair.

2 increase or decrease the natural luster of hair.

3 modify bleached hair.

Deepen the color of natural hair.

Triple bleaching principle

1 bleaching principle:

1) dioxide is a bleaching substance to eliminate pigments.

Reduce natural pigments and make hair bright.

Hair bleaching goes through the following steps:

Black-brown-red-golden yellow-golden yellow-light yellow

2. Operation method of bleaching

1) Don't wash your hair before bleaching.

2) If your hair is really dirty, you can wash it lightly, but don't scratch your head when washing your hair, so as not to scratch your scalp.

3) mixed bleach:

Bleaching powder: molecular oxygen reaction rate

1: 3 slow

1: 1 Come on

3 bleaching powder classification:

1) Dust bleaching powder: coarse particles, quick reaction and difficult to master.

2) Dust-free bleaching powder: fine particles, slow reaction and easy to master.

PS: 1 Neither hydrogen peroxide nor bleaching powder can bleach natural pigments. The mixture of molecular oxygen and bleaching powder has a greater bleaching effect on natural pigments than artificial pigments.

Four principles of hair dyeing

Hair dye passes through the cuticle protective film and deposits on the hair cortex, which makes the hair discolored and shiny.

1 hair dyeing program

1) Wash your hair and blow dry.

2) Apply anti-allergic cream to the hairline of hair. From the back, apply the dye from the low temperature area of the customer to the high temperature area.

2 coating method

1) Short method:

A, starting from the back of the head, apply dye at a distance of 1.5cm from the hair end to the hair root.

B, wait for 20-30 minutes.

Then apply the dye to the hair roots.

Wait 10-20 minutes.

2) Long hair

A, starting from the cold zone, starting from the hair end.

B, wait for 20-30 minutes.

C, from the middle to the hair root1.5cm.

D, wait 10-20 minutes.

E, the remaining hair roots continue to be coated with dye.

F, wait 10-20 minutes.

PS: 1。 Because of the large resistance of the hair end, more dyes should be put in the hair end to absorb more colors, so as to obtain uniform expected colors.

2. See half of the heating time.

Five-color principle: it is the impression produced by light waves emitted, reflected or transmitted by objects through vision.

1 main color (primary color)

Red, yellow and blue

Secondary colors (secondary colors) orange, green and purple.

Red+yellow orange