Hair coloring today is not only about painting over gray hair or changing color. The winners in the market are those companies that offer customers a solution to their ever-growing needs and satisfy a wide variety of desires for hair dyeing services. For more references, check out: jazzing hair color
Once again about the structure of hair
Hair is made up of keratin, a protein that contains 16 amino acids. It is enriched with trace elements (iron, copper, zinc, chromium, manganese, sulfur) and vitamins A, B, PP, C, H. In addition, healthy hair contains water, lipids and pigments.
Each hair has three layers.
The outer layer, or cuticle , is responsible for its appearance as well as its porosity (hygroscopicity). It consists of 6-9 layers of flat transparent cells, which are located on the surface of the rod, like fish scales, and are horny scales containing hard keratin. The cuticle protects the hair from adverse external influences, and the fatty acids that hold the scales together provide smoothness and shine to the hair. The cuticle takes up approximately 13.5% of the hair volume.
Under the cuticle is the cortex , a cortical substance that occupies 80% of the hair volume and consists of layers of elongated spindle-shaped cells that give the hair strength and elasticity. The cortex is made up of keratin, which contains pigment (melanin). The cortex is responsible for the mechanical properties of the hair - strength, elasticity, shape and structure. The cells of this layer also contain pigments that determine hair color: eumelanin (black-brown) and pheomelanin (yellow-red). The whole variety of human hair color depends on the ratio of these pigments.
Eumelanin is characterized by its shape (large, elongated molecules) and the presence of primary primary colors (red, yellow and blue). The main task of eumelanin is to give the hair a level of depth of tone and color direction. The more (quantitatively) eumelanin is saturated, the darker the hair, the less it, the lighter the hair (in very light hair, eumelanin is practically absent and oxygen molecules are present in its place).
Pheomelanin consists of very small rounded molecules of two colors - red and yellow. It is very difficult to remove pheomelanin from hair. And its complete removal is almost impossible and in most cases leads to the destruction of the hair. Pheomelanin influences the result of staining and is characterized by the manifestation of unwanted orange, yellowish and reddish hues.
The clear effect of pheomelanin on hair coloring is noticeable when bleaching and lightening hair. Theomelanin is responsible for the background clarification.
Medulla (medulla) is the core of the hair. It consists of soft keratin cells and air cavities. Medulla has practically no effect on coloring and may be completely absent from the hair. The main task of the medulla is thermoregulation.
Types of hair dyes
There are many different dyes for hair, but with all the variety they can be combined into clear groups that all firms adhere to, regardless of country and chemical formulas. Dyes are classified according to the type of chemical reactions and application:
permanent dyes (when using them, a long-lasting dyeing effect is achieved, up to 4-8 weeks (these numbers mean that during this time the intensity of the selected dye shade will decrease ("wash out") and hair roots will grow, re-staining will be required), due to the penetration of the dye into the cortical layer of the hair (the layer in which the melanin pigment is localized), reducing the amount of natural pigment in the hair and / or adding cosmetic pigments of various shades and intensities);
toning dyes (the dye remains on the hair for a short period of time (washed off after 3–6 times of shampooing) due to the fact that dyes do not dye the hair inside, but envelop it and close the cuticle scales);
bleaching dyes (the only type of dye that does not create color, but only bleaches hair, destroying both natural and artificial pigments);
vegetable dyes (unlike the above, they are not synthetic, they are made on the basis of acidic natural dyes; they act due to the penetration of vegetable dye particles under the influence of heat into the cortex).