There are three types of perm methods: alkaline, acid, and exothermic. The latter two are part of the "hot" perm treatment process, which means the solution is applied before heat. A "cold" perm ...

Hair perm waving solutions are either acid or alkaline. Acid: Acid perm solutions have low pH balances, typically between 4.5 and 7. They aren’t as strong as alkaline solutions, making acid ...

After wet hair has been wrapped in rollers (the smaller the rollers the tighter the curls) a chemical solution containing either sodium thioglycolate (alkaline perm) or glycerol monothioglycolate ...