Which bond is primarily affected by chemical processing in a permanent wave?

• A. Salt bonds
• B. Hydrogen bonds
• C. Peptide bonds
• D. Disulfide bonds

Answer: (D)

Permanent waves change the shape of hair by altering the bonds that hold Keratin in its natural form. The key bonds involved are the disulfide bonds between cysteine residues. A reducing agent in the permanent-wave solution breaks these covalent S-S bonds, allowing the hair to be reshaped around rods. After the desired shape is set, a neutralizer oxidizes the hair to reform disulfide bonds in the new configuration, locking in the curl or wave.

Salt bonds and hydrogen bonds do play a role in how hair behaves and can be affected by processing conditions like pH and moisture, but they are much weaker and not the primary chemical bonds changed during permanent waving. Peptide bonds, which make up the protein backbone, aren’t targeted in this process.