Which bonds are typically targeted during chemical hair relaxing and perms to change hair shape?

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

Answer: (C)

Chemical hair relaxing and perms work by changing the shape of the hair through breaking and reforming disulfide bonds in the keratin of the cortex. These bonds connect cysteine residues on different parts of the protein, forming strong covalent cross-links that largely determine curl pattern and overall structure. A reducing agent in the relaxer or perm solution breaks these disulfide bonds, making the hair pliable enough to be reshaped. After the hair is placed in the desired position, a neutralizer oxidizes the hair and re-formulates disulfide bonds in the new configuration, locking in the straightened or curled shape.

Hydrogen bonds and salt bonds are weaker and easily disrupted by moisture, heat, or changes in pH, so they don’t provide lasting shape on their own. Peptide bonds are the protein backbone links and aren’t targeted in typical salon texturizing processes, as altering them would damage the hair structure.