Tennessee Barber Practice Exam 2025 – The All-in-One Resource to Master Your Licensing Test!

The primary role of hydrogen peroxide in most hair dyes is as an oxidizing agent. It helps to lift the hair's natural color by breaking down the pigments, making it possible for the dye to deposit the new color into the hair shaft. This oxidation process is essential for achieving the desired shade, especially in permanent hair dyes, where a chemical reaction is needed to change the hair color.

While ammonia is often included to help facilitate the dyeing process by opening the hair cuticle, its function is more about preparing the hair for the dye rather than being the main ingredient in terms of color change. Glycerin can serve as a conditioning agent, and alcohol may be included as a solvent or carrier in some formulas, but neither of these substances plays a central role in the actual coloring process as hydrogen peroxide does. Therefore, hydrogen peroxide is correctly identified as the main ingredient in most hair dyes.