California Cosmetology Written ExamChemical Texture ServicesMedium
A stylist is choosing between an alkaline permanent wave and an acid (glyceryl monothioglycolate) wave for a client with fine, color-treated hair. Which characteristic distinguishes the acid wave from the alkaline wave?
- AAcid waves have a pH near 6.5–7.9, process more slowly, and typically require heat
- BAcid waves swell the hair shaft more than alkaline waves and cause more damage
- CAcid waves have a pH of 9.0–9.5 and process faster than alkaline waves
- DAcid waves use ammonium thioglycolate as the primary reducing agent
Show answer & explanationAnswer & explanation
Correct answer: A. Acid waves have a pH near 6.5–7.9, process more slowly, and typically require heat
Acid waves use glyceryl monothioglycolate (GMT) with a lower pH (about 6.5-7.9), producing softer curls with less swelling and damage than alkaline waves, but they process more slowly and usually require added heat (thermal wraps or hood dryers) to activate.
Why the other options are wrong
- B. Alkaline waves cause more swelling and are generally harsher on the hair.
- C. That pH range describes alkaline waves, not acid waves.
- D. Acid waves use glyceryl monothioglycolate, not ammonium thioglycolate.
Acid (GMT) Permanent Wave
A gentler perm using glyceryl monothioglycolate at a lower pH (6.5-7.9) that processes slower and often needs heat to activate.
- Lower pH than alkaline waves = less swelling/damage
- Requires heat (thermal wrap or dryer)
- Better suited to fine, color-treated, or delicate hair
Memory trick: Acid waves are gentle and need a warm hug (heat) to work slowly.