- Hair is washed with mild shampoo (no conditioner) & dried completely.
- Perming lotion is added to soften the hair (break the chemical bonds) & is washed off.
- The hair is then heated between 2 metal plates which straightens the hair. Here the chemical bonds are connected again.
Sodium hydroxide is a caustic chemical that can burn the skin, and break or damage hair. The stronger the solution used (for better effects), the more potential damage can occur to the hair.
Guanidine hydroxide is less damaging than sodium hydroxide, but it may still damage hair and it can definitely de-fat the scalp. The treatment can cost up to over US $ 500, and lasts only 4-6 months.
Ammonium Thioglycolate is a known cause of irritant contact dermatitis in hairdressers and their clients.