Michigan Cosmetology Licensing Practice Exam 2026 - Free Cosmetology Practice Questions and Study Guide

The primary ingredient in most hair relaxers is sodium hydroxide. This chemical, often referred to as lye, works by breaking down the protein structure of the hair, allowing the hair to be straightened. Sodium hydroxide is highly effective and is commonly used in both professional settings and at-home hair relaxing products due to its strong alkaline properties, which can alter the pH of the hair.

In the context of hair relaxers, sodium hydroxide is chosen for its ability to provide significant straightening effects, especially on coarse or tightly curled hair types. While ammonium thioglycolate is another ingredient that can be used in hair treatments, it is more commonly found in perm solutions rather than relaxers. Cetyl alcohol and glycolic acid serve different purposes in hair care products, such as acting as emulsifiers or conditioning agents, but they do not provide the fundamental straightening action characteristic of relaxers.