Illinois Cosmetology Practice Exam 2025 – 400 Free Practice Questions to Pass the Exam

The main ingredient in most permanent wave solutions is ammonium thioglycolate. This compound is crucial in the permanent waving process, as it acts as a reducing agent that breaks the disulfide bonds in the hair. This allows the hair to be reshaped and "set" into new configurations, creating curls or waves.

Ammonium thioglycolate works effectively because it is alkaline, which helps open the hair cuticle, allowing the solution to penetrate and modify the hair's internal structure. This is necessary for achieving the desired wave or curl without causing excessive damage.

In contrast, other options such as calcium hydroxide are used in some hair processes but are not the primary ingredient in most permanent wave solutions. Hydrogen peroxide is primarily known as a bleaching agent or an oxidizing agent and is not used in the curling process. Glycolic acid, while used in various hair products for its exfoliating properties, does not play a role in the chemical structure transformation involved in permanent waving. Therefore, ammonium thioglycolate stands out as the essential component in permanent wave solutions.