New York State Cosmetology Practice Exam 2025 – The All-in-One Guide to Master Your Certification!

Ammonium thioglycolate is the chemical commonly used in permanent waving, and its selection as the correct answer is based on its specific function and properties in the hair perming process. This chemical acts as a reducing agent that breaks the disulfide bonds in the hair, allowing it to be reshaped into curls or waves.

When combined with heat and the appropriate wrapping techniques, ammonium thioglycolate softens the hair's protein structure, making it malleable for styling. Once the desired shape is achieved, a neutralizer is applied, which helps to re-establish the disulfide bonds in the new shape, effectively setting the perm.

While sodium hydroxide is also a chemical used in some permanent waving processes, often referred to as a "lye" relaxer, it serves a different purpose by removing curls rather than adding them. Hydrogen peroxide is primarily used as a developer in hair color applications rather than in the waving process itself. Calcium carbonate does not typically play a role in hair treatments in the same way, making ammonium thioglycolate the best choice for permanent waving.