What is the principal ingredient in most hair color products?

The principal ingredient in most hair color products is ammonia. Ammonia serves as an alkaline agent that opens the hair cuticle, allowing the color or dye to penetrate the hair shaft effectively. This is essential for achieving long-lasting results because if the hair cuticle isn't opened, the color molecules cannot effectively enter the hair, leading to a less vibrant outcome.

In addition, ammonia helps to maintain the pH balance necessary for the chemical reactions involved in the hair coloring process. While hydrogen peroxide is often mentioned due to its role as an oxidizing agent in many hair dyes, it primarily interacts with the dye itself rather than serving as the main component responsible for opening the cuticle. Alcohol and glycerin are generally used as solvents and conditioning agents, respectively, but they do not play the critical role that ammonia does in facilitating effective hair coloring.