Hair dye is a general term for a large class of special-purpose cosmetics. According to the definition of "Safety and Technical Specifications for Cosmetics", hair dye is a substance added to cosmetics to change the color of hair. In a broad sense, products aimed at changing hair color are called hair dyes. According to the length of coloring time for hair, they are divided into temporary hair dyes, semi-permanent hair dyes, and permanent hair dyes; according to the principle of hair dyes, they can be divided into Oxidative hair dyes and non-oxidative hair dyes. Hair dye allergy Allergic contact dermatitis caused by hair dyes can manifest as redness, swelling, itching, and burning pain on the scalp in mild cases, and swelling, blisters, yellow water on the scalp, neck and face in severe cases, and even purulent infection.
There is a chemical substance called 'p-phenylenediamine' in the ingredients of hair dye, which is easy to cause damage to human skin. The more frequently the hair is dyed, the closer the chemical reagent is in contact with the scalp during hair dyeing, the greater the harm to the body, and the greater the chance of hair dye allergy. In the past, a lot of chemicals were used to dye hair, but now there are many natural pure plant hair dyes; plant hair dyes are extracted from a certain part of the plant, usually in powder form, not in paste form, which are more commonly used in the market There are henna, avocado, Polygonum multiflorum, etc. The difference between the hair dyeing principle of plant hair dyes and chemical hair dyes is that plant hair dyes are just like our nails, that is, a layer of color is brushed on the surface, and it will not blend into the hair. Go inside, it will not be dyed inside the hair core like chemical hair dyes.
Vegetable hair dyes are generally in powder form, while chemical hair dyes are in paste form, and hydrogen peroxide milk is indispensable in chemical hair dyes. If there is hydrogen peroxide milk in the hair dye, it cannot be called pure plant Hair dye; plant hair dye is generally mixed with warm water, you can add honey, salt, olive oil, etc. instead of using hydrogen peroxide to mix.