California Cosmetology Practice Exam 2026 – 400 Free Practice Questions to Pass the Exam

Ammonium thioglycolate is the primary chemical compound used in permanent wave solutions because it functions as a reducing agent that breaks down the disulfide bonds in the hair's keratin structure. This process allows the hair to be reshaped into a new style. When the hair is treated with this compound, it becomes pliable, enabling the stylist to manipulate it into curls or waves as desired.

After the desired shape has been achieved, a neutralizer is applied to the hair to reform the disulfide bonds in this new configuration, ensuring that the curls or waves are set in place. This effectiveness is why ammonium thioglycolate is the industry standard for creating permanent waves.

The other compounds mentioned have different functions and are not used for the permanent waving process. Sodium sulfate, for instance, is often used in cosmetic formulations as a thickener or emulsifier but does not have the properties that allow for altering the hair structure for permanent waves. Hydrogen peroxide is typically used as a bleaching agent or a developer in hair coloring processes rather than for perming, and calcium carbonate is generally not involved in chemical hair treatments. Understanding these roles helps clarify why ammonium thioglycolate is the key ingredient in permanent wave solutions.