Hair that is treated with hydroxide relaxers must not be treated with _____.

• A. Sodium hydroxide relaxers
• B. Calcium hydroxide relaxers
• C. Potassium hydroxide relaxers
• D. Ammonium thioglycolate relaxers

Answer: (C)

Hair that has already been treated with a hydroxide relaxer is in a highly alkaline, weakened state because the relaxer opens disulfide bonds in the hair. Introducing another strong-base chemical—especially a potassium hydroxide relaxer—pushes the pH even higher and can push the hair into over-processing, leading to severe damage, breakage, or unacceptable texture. For that reason, a potassium hydroxide relaxer should not be used on hair that has already been relaxed with hydroxide.