Do you need to wash your hair before dyeing it? It actually causes such a big harm

Hair dyeing is the most common thing in daily life. Some people will inevitably ask whether it is necessary to wash their hair before dyeing. Professionals recommend that it is best not to wash your hair before dyeing it. If you must wash your hair, it is best to do it two or three times before dyeing it.

This is because the principle of hair dyeing is to open the hair cuticles on the surface of the hair so that the hair dye particles can enter the hair smoothly. However, the scalp is the place with the most and densest hair follicles in the human body. The harmful substances in hair dye can easily enter the human body through the hair follicles. Therefore, even if the hair dye does not directly contact the scalp, it will form gas and enter the body through volatilization. The oil on the scalp can resist these harmful substances, which is why you should not wash your hair before dyeing it.

If you must wash your hair before dyeing it, just wash away the dust or dirt on the hair. Do not rub your scalp to clean off all the oil. Also, when washing your hair, the water temperature should not exceed 40 degrees. Only in this way can the oil play its protective function. In addition, after washing your hair, you should apply a scalp isolation cream before dyeing your hair. Do a good job of isolation and maintenance before dyeing your hair to minimize the damage to your scalp caused by dyeing.

Expert doctors point out that some ingredients in hair dye are toxic. Its main toxic substance is benzene. According to Qiu Bingyi, former member of the Cosmetics Hygiene Standards Committee of the Ministry of Health and professor at South China Normal University, my country's current standards for the content of metaphenylenediamine in hair dye cosmetics were formulated in reference to the EU's new standards in 2007, which stipulate that metaphenylenediamine shall not be added.

It is best not to dye your hair frequently, 2-3 times a year at most. Too frequent dyeing can cause great damage to your hair. In addition, when dyeing your hair, avoid direct contact of the dye with your skin. If you accidentally get sprayed, apply Vaseline or wipe it off immediately.

Investigations have shown that 90% of hair dyes on the market have the potential to cause cancer. Even some hair dyes that emphasize "plant essences" have the potential to cause cancer. Although the harm of this hair dye is relatively small, it is impossible to be completely harmless because it must contain the ingredient "phenylenediamine" that makes hair darker.