Acid Perm vs. Alkaline PermQ: Please explain the difference of an acid perm vs. an alkaline perm. When should you use what and on what type of hair?
A: The difference between acid waves and alkaline waves are basically this:
Acid waves usually have a pH rating between 4.5 and 7.0 and require heat to speed processing. The main ingredient in an acid perm is glyceryl monothioglycolate. Since hair has a pH of around 5.0 acid waves are less damaging to the hair, require the heat of a dryer usually and typically do not produce as firm a curl as an alkaline wave. You will want to use acid waves for those individuals with very fine textured hair or those whose hair is damaged or has been processed with other harsh chemical services again.
Alakine waves are made using an alkaline ingredient, generally ammonium thioglycolate. They are also usually between 9.0 and 9.6 in pH. Alkaline waves are also called "cold waves" since they don't need any extra heat source to process. These work best on hair that is coarse, thick or resistant to processing as well as "normal" virgin hair as they are much stronger when compared to Acid waves.
The different formulations for perms
Is there a difference between a permanent wave processed with or without heat?