What is the difference between permanent and semi-permanent hair color?

Permanent hair color is designed to penetrate the hair shaft and alter the natural pigment within the hair, providing a long-lasting change in color. This is achieved through a chemical process that opens the cuticle layer of the hair, allowing the color molecules to enter and bond with the hair structure. As a result, permanent color often endures through multiple washes and can cover gray hair effectively.

In contrast, semi-permanent hair color typically does not penetrate the hair shaft in the same way; instead, it coats the hair cuticle. This type of color usually contains smaller dye molecules that can only partially enter the hair, allowing for temporary color changes that gradually fade over time with washing. This means that while semi-permanent color provides a vibrant look, it doesn’t offer the same durability or coverage as permanent hair color.

Understanding this fundamental difference between how these two types of hair color interact with the hair structure is crucial in making informed decisions about hair coloring techniques and desired outcomes.