During chemical processing of hair, the action that fixes the new shape is called

• A. Neutralization
• B. Reduction
• C. Oxidation
• D. Hydration

Answer: (A)

The action that fixes the new shape is neutralization. After the hair’s disulfide bonds are temporarily broken during the reducing stage and the hair is reshaped, neutralization serves two crucial roles: it stops the reducing agent from continuing to soften bonds, and it re-forms the disulfide bonds in the new configuration by using an oxidizing agent (typically hydrogen peroxide). This oxidation locks the hair into its new curl or straightened form and restores the hair’s structure and pH, effectively setting the shape. Hydration isn’t the step that fixes the shape, and while oxidation occurs during neutralization, the term that describes the overall action of stabilizing the change is neutralization.