In acid waves, the primary reducing agent is which of the following?

• A. Glycerl monothioglycolate
• B. Glyceryl monothioglycolate
• C. Sodium metabisulfite
• D. Sodium sulfite

Answer: (A)

In acid waves, the substance that does the primary reducing work is a thioglycolate compound with a glycerol backbone. This reagent, glyceryl monothioglycolate, donates sulfhydryl groups to the hair’s disulfide bonds, converting -S-S to two -SH groups. That reduction loosens the cross-links in the cortex, making the hair pliable enough to mold into the desired shape.

After wrapping, a neutralizer oxidizes those thiol groups back into disulfide bonds, locking in the new curl. The other options—sodium metabisulfite and sodium sulfite—are not used as the main reducing agent in acid waves; they don’t provide the same thiol-based reduction needed to break disulfide bonds in this process.