A correct permanent wave service alters only what bonds

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

Answer: (D)

Permanent waving changes hair by altering the bonds that hold keratin strands together, specifically the side bonds. The chemistry uses a reducing agent to break the disulfide bonds, which lets the hair be reshaped around rods. After shaping, a neutralizer re-forms those bonds in the new configuration, freezing the curl in place. The peptide bonds that form the protein backbone stay intact, and while hydrogen and salt bonds can be affected temporarily during processing, the lasting modification comes from the disulfide connections within the side bonds. So the bonds that are altered in a permanent wave are the side bonds.