In permanent waving, the reduction reaction is due to the addition of which chemical?

• A. Hydrogen
• B. Oxygen
• C. Nitrogen
• D. Carbon dioxide

Answer: (A)

Permanent waving works by breaking the hair’s disulfide bonds and then re-forming them in a new shape. The reduction step achieves this by adding hydrogen atoms to the sulfur atoms in the bonds, converting disulfide (-S-S-) into two sulfhydryl (-SH) groups. The hydrogen comes from the reducing agent used in perms (such as ammonium thioglycolate), which donates hydrogen to the bonds. Therefore, hydrogen is the chemical responsible for driving the reduction reaction in this process. Oxygen would promote oxidation instead, and nitrogen or carbon dioxide don’t participate in this reduction step. After shaping, a neutralizer then re-oxidizes the sulfhydryl groups to re-form disulfide bonds and lock in the new curl.