Which type of hair color is known to penetrate the hair shaft and last longer?

Permanent hair color is specifically designed to penetrate the hair shaft and provide long-lasting results. This type of hair color contains a combination of ammonia and peroxide, which opens the cuticle layer of the hair and allows the color molecules to enter the cortex. Once inside, these color molecules react with the natural pigments in the hair, creating a lasting change in color that is resistant to washing and fading.

Unlike temporary and semi-permanent hair colors, which typically coat the outer layer of the hair and do not offer the same level of durability, permanent hair colors ensure a longer-lasting effect. Temporary colors are often easily washed out and last only until the next shampoo, while semi-permanent colors may last several weeks but will eventually fade as they don't provide the same depth of penetration as permanent options. Gel-based hair color can refer to various formulations, but unless specified as a permanent type, it does not guarantee the long-lasting change that permanent hair color provides.