What happens when the reducing agent reduces disulfide bonds in hair during a perm processing?

• A. The bonds break and allow rearrangement into new curl pattern.
• B. Disulfide bonds become stronger.
• C. Keratin is removed.
• D. Hair becomes permanently straight.

Answer: (A)

Disulfide bonds in hair keratin help lock in its natural shape. When a perming solution with a reducing agent is applied, those bonds are broken by converting the disulfide linkages into sulfhydryl groups. That break makes the hair matrix pliable, so the strands can be reshaped around rods into a new curl pattern. Once the hair is in position, a neutralizer re-oxidizes and re-forms disulfide bonds in the new arrangement, effectively locking in the curl.

So the reducing agent’s job is to break the bonds to allow rearrangement. It doesn’t strengthen bonds, remove keratin, or straightens hair by itself; the new shape is secured as the bonds reform in the new pattern.