Nevada State Board of Cosmetology Practice Exam

Permanent hair color provides the longest-lasting results because it is designed to penetrate the hair shaft and alter the natural pigment of the hair. This type of color uses a chemical process that includes both an oxidizing agent and ammonia, which open the hair cuticle, allowing the color to deposit and bind within the hair structure. As a result, permanent hair color can last through multiple washes and can only be removed by growing out or cutting the hair.

In contrast, temporary hair color coats the hair shaft without penetrating it, leading to results that typically last until the next shampoo. Demi-permanent hair color, while longer-lasting than temporary options, still does not provide the same level of permanence because it does not contain ammonia and uses a lower level of developer. Semi-permanent hair colors also coat the hair but usually fade much quicker than permanent colors, often lasting only a few weeks. Therefore, among all the options, permanent hair color is the best choice for those seeking a long-lasting effect.