What type of hair color contains the highest concentration of ammonia?

Permanent hair color contains the highest concentration of ammonia because it is formulated to penetrate the hair shaft and provide long-lasting results. The ammonia in permanent hair color acts as an alkaline agent, opening the hair's cuticle layer to allow the color to deposit into the cortex. This process enables the color to be more permanent and resistant to fading compared to other types of hair color, making it ideal for clients seeking a long-lasting change.

In contrast, temporary hair colors typically contain little to no ammonia, as they are designed to simply coat the outer layer of the hair without making permanent changes. Demi-permanent hair colors also use a lower concentration of ammonia or sometimes ammonia-free formulas, allowing for a more gentle process that provides semi-permanent results but does not involve as much lifting of the natural hair color. Highlights may involve the use of lighteners that can also be ammonia-free or contain lower levels of ammonia, primarily targeting specific strands rather than the whole hair shaft.