South Carolina Cosmetology Practice Exam

Ammonium thioglycolate is the chemical commonly found in permanent wave solutions. This compound acts as a reducing agent in the perm process, allowing the hair's disulfide bonds to be broken and reformed in a new shape, enabling the curls or waves to set in. When the hair is exposed to heat during the perming process, ammonium thioglycolate helps soften the hair structure so it can be molded into the desired style. Once the hair is set, a neutralizer is applied to help rebuild the disulfide bonds in their new configuration, giving the hair its new textured form.

Other chemicals listed, such as sodium chloride, primarily serve as salt and may help with the overall solution's effectiveness, but they are not the active agents responsible for creating curls. Hydrogen peroxide is commonly used as a lightening agent or a developer in hair coloring processes, while glycolic acid is often associated with skin care and chemical exfoliants, not with permanent waving solutions. Each of these plays a different role in cosmetology, but ammonium thioglycolate is specifically tailored for altering hair texture through perming.