Which common chemical is used in hair coloring?

Ammonia is a crucial component in many hair color formulations due to its ability to open the hair cuticle, allowing the color to penetrate into the hair shaft. The alkaline nature of ammonia helps in the process of oxidation, which is essential for the development of the dye molecules that create long-lasting color. Without ammonia, the hair color would not effectively penetrate, limiting its longevity and vibrancy.

While hydrogen peroxide is also an important chemical in hair coloring, as it serves as an oxidizing agent that activates the dye and lightens the hair, it works in conjunction with ammonia to achieve effective results. Sodium chloride is typically used for other purposes in cosmetics and is not directly involved in the coloring process, while ethyl alcohol serves different functions, such as acting as a solvent, but doesn't play a primary role in hair dyeing itself. Thus, ammonia is most widely recognized for its specific effectiveness in hair coloring applications.