An acid with a low pH that is the primary reducing agent in acid waves is which compound?

• A. Glycerl monothioglycolate
• B. Glyceryl monothioglycolate
• C. Glyceraldehyde
• D. Ammonium thioglycolate

Answer: (A)

Acid waves rely on a thiol-containing reducing agent that can work at low pH to break the hair’s disulfide bonds, allowing the hair to be reshaped. The compound used for this purpose is glyceryl monothioglycolate, whose thioglycolate group donates electrons to reduce those bonds in keratin. The acidic environment helps keep the solution effective and supports penetration and softening during processing, so the hair can set into the new shape when neutralized. Ammonium thioglycolate, in contrast, is the reducing agent used in alkaline waves, not acid waves, and glyceraldehyde is a simple sugar with no role as a reducing agent in waving chemistry. The first option, despite a spelling variation, points to the correct substance responsible for acid-wave reductions.