Nevada Barber Practice Exam 2025 - Free Barber Practice Questions and Study Guide

The active ingredient in many chemical hair relaxers is sodium hydroxide. This compound is a strong alkaline substance that works by breaking down the protein structure of the hair, allowing it to be restructured into a straighter form. Sodium hydroxide is effective for this purpose because it raises the pH of the hair, which helps to swell and soften the cuticle layer.

In contrast, other substances listed serve different roles in hair treatment. For example, ammonium thioglycolate is typically found in permanent waves and some relaxers, but sodium hydroxide is more commonly associated with the traditional hair relaxation process. Hydrogen peroxide is widely used as a bleaching agent rather than in relaxers, while glycolic acid often serves as an exfoliant or moisturizer in various beauty products but is not used for relaxing hair. The strong nature of sodium hydroxide and its ability to effectively alter the hair's structure is why it is the primary ingredient in many hair relaxers.