New Mexico Cosmetology Practice Exam 2026 – All-in-One Guide to Mastering Your Certification!

The chemical commonly used to relax curly hair is sodium hydroxide. This compound functions as a powerful alkaline agent, breaking down the disulfide bonds in the hair's protein structure, allowing the natural curl pattern to be altered to a straighter form. This process is known as chemical hair relaxing, and sodium hydroxide is particularly effective for this purpose.

Sodium hydroxide's role in the process makes it ideal for individuals seeking a smoother and more manageable hairstyle by permanently altering the hair's texture. Its application requires careful handling, as it can be harsh on the hair if not used correctly, but when applied properly, it yields significant results in hair smoothing and straightening.

Other chemicals listed, while they have various uses in hair treatment processes, do not serve the same primary function. Ammonium thioglycolate is also used for hair relaxing but is a different compound altogether, often considered gentler than sodium hydroxide. Hydrogen peroxide is typically used as a bleaching agent and not for relaxing hair. Glycolic acid is primarily used in skincare products and does not relate directly to hair relaxing treatments.