What role does ammonia play in permanent hair color?

Ammonia plays a crucial role in the process of permanent hair color by opening the hair cuticle, which allows the color to penetrate the hair shaft effectively. The hair cuticle is made up of overlapping layers of cells that protect the inner structure of the hair, and for color to be deposited successfully, these layers need to be lifted. When ammonia is present in the hair color formulation, it raises the pH balance of the hair, causing the cuticle to swell and separate. This creates pathways through which the color molecules can enter the hair, ensuring that the color change is long-lasting and effective.

The cuticle's lifting is essential for the chemical reaction that enables the permanent dye to bond with the natural pigments in the hair, leading to the desired color result. Without the action of ammonia, the color would struggle to penetrate the hair properly, resulting in less effective coloring.