A client's hair was chemically relaxed using ammonium thioglycolate rather than sodium hydroxide. Which statement accurately describes how this relaxer breaks disulfide bonds?
- AIt breaks disulfide bonds through a reduction reaction, and bonds are reformed in the new shape once neutralized with an oxidizer
- BIt converts cystine bonds into lanthionine bonds through an irreversible chemical reaction
- CIt swells the cuticle to physically snap disulfide bonds through mechanical tension alone
- DIt uses an oxidation reaction to permanently lengthen the polypeptide chains before neutralizing
Show answer & explanationAnswer & explanation
Correct answer: A. It breaks disulfide bonds through a reduction reaction, and bonds are reformed in the new shape once neutralized with an oxidizer
Ammonium thioglycolate relaxers work by reduction (the same chemistry as thio perms), temporarily breaking disulfide bonds so the hair can be smoothed into a new straight shape; an oxidizing neutralizer then reforms the bonds in that position. This differs from hydroxide relaxers, which cause an irreversible lanthionization reaction.
Why the other options are wrong
- B. Lanthionization is the irreversible reaction caused by hydroxide relaxers, not thio relaxers.
- C. Bond breaking is chemical (reduction), not purely mechanical.
- D. Relaxers use reduction to break bonds first, not oxidation to lengthen chains.
Thio Relaxer Chemistry
Ammonium thioglycolate relaxers break disulfide bonds via reduction; an oxidizing neutralizer then reforms bonds in the newly straightened position, unlike the irreversible lanthionization of hydroxide relaxers.
- Uses reduction, same as thio perms
- Requires oxidative neutralization to fix new shape
- Contrasts with hydroxide relaxers' irreversible lanthionization
Memory trick: 'Thio Trades bonds temporarily, hydroxide Hardens them forever'