Connecticut Hairdresser Licensure Practice Exam 2025 - Free Hairdresser License Practice Questions and Study Guide

Sodium hydroxide is commonly used in hair relaxers for the purpose of straightening hair. It is a strong alkaline substance that breaks down the protein bonds in the hair shaft, allowing curly or wavy hair to become straight. This ingredient effectively reshapes the hair's structure by altering the disulfide bonds, which is crucial for achieving a smoother and straighter appearance.

Within the context of hair relaxers, sodium hydroxide is particularly effective for coarse and resistant hair types. Its potency requires careful application to avoid damage to the hair and scalp, thus making proper technique and timing essential during the relaxing process.

Other ingredients, such as calcium hydroxide and ammonium thioglycolate, may also be utilized in hair treatments but serve different purposes or are not as commonly associated with traditional relaxers as sodium hydroxide. Propylene glycol is more commonly found in hair conditioning products due to its moisture-retaining properties rather than in relaxers aimed at straightening hair. This distinction helps clarify why sodium hydroxide is the preferred choice in relaxer formulations for effectively straightening hair.