Acid, Alkaline or Cysteamine Perm: Which Is Right for Your Client?
Not all perms work the same way. Choosing the right professional hair perm depends on the client’s hair condition, texture and the result they want.
The three main systems are alkaline perms, acid perms and cysteamine perms.
Alkaline Perm
An alkaline perm usually contains ammonium thioglycolate and has a higher pH. It causes more hair swelling, allowing the product to penetrate quickly and create a stronger curl. It is best for:
- Virgin or resistant hair
- Coarse hair
- Strong, defined curls
- Clients wanting longer-lasting curl
Avoid or use extreme caution on highly bleached, damaged or very porous hair.
Acid Perm
An acid perm generally uses glyceryl monothioglycolate (GMTG) and has a lower pH. It causes less swelling and usually processes more slowly, often with heat. It is best for:
- Fine or porous hair
- Some coloured hair, when permitted by the manufacturer
- Softer, more natural curls and waves
- Hair that may not tolerate a traditional alkaline perm
An acid perm is gentler in terms of hair swelling, but it can still cause damage if the hair is unsuitable or over-processed.
Cysteamine Perm
A cysteamine perm uses cysteamine or cysteamine HCl rather than traditional thioglycolates. It is a different reducing system and is often formulated to provide a gentler restructuring of the hair. It is best for:
- Creating softer curls and movement
- Certain coloured or sensitised hair types, where the manufacturer allows it
- Clients who may not be suitable for a traditional alkaline perm
Importantly, cysteamine HCl does not automatically mean the product is an acid perm. The finished product’s pH and complete formulation must be considered.
Which Perm Should You Choose?
| Hair type / result | Consider |
| Coarse, resistant or virgin hair | Alkaline perm |
| Fine, porous or suitable coloured hair | Acid perm |
| Softer restructuring / certain sensitised hair | Cysteamine perm |
| Strong, defined curl | Alkaline perm |
| Softer, natural-looking wave | Acid or cysteamine perm |
The Golden Rule
Always assess the hair before choosing a permanent wave. Check the hair’s condition, porosity, elasticity, previous colour or chemical services and desired result. A strand test is recommended when there is any doubt.
The right acid, alkaline or cysteamine perm isn’t simply the strongest product—it’s the one that is appropriate for the client’s hair and the result you want to achieve.