Iowa Cosmetology Practice Exam 2025 - Free Cosmetology Practice Questions and Study Guide

Sodium hydroxide relaxers are a common type of chemical relaxer used in hair services primarily to straighten curly or wavy hair. This relaxer works by breaking down the disulfide bonds in the hair’s keratin structure, allowing the hair to be reshaped into a straighter form. Sodium hydroxide is highly alkaline and can penetrate the hair shaft effectively, making it a popular choice for those who have coarse or resistant hair textures.

In contrast, while glycerin, calcium hydroxide, and potassium relaxers do exist, they are not as widely recognized or used compared to sodium hydroxide relaxers. Glycerin is more commonly associated with moisturizing properties rather than as a primary ingredient in relaxers. Calcium hydroxide is often found in no-lye formulations but is not as prevalent as sodium hydroxide. Potassium relaxers, while they do exist, are less commonly used compared to sodium hydroxide options, which have a longer history and established efficacy in professional hair services.

Thus, sodium hydroxide is recognized as a primary relaxer because of its effectiveness, especially in professional settings where strong and enduring results are often desired.