Ace the South Dakota Cosmetology Test 2025 – Style Your Future with Confidence!

The main difference between permanent and semi-permanent hair color lies primarily in their formulations and the resulting longevity of the color on the hair, which pertains to their lightening abilities. Permanent hair color contains a high level of ammonia and an oxidative agent that allows it to penetrate the hair shaft more deeply. This enables the color to lighten existing pigments in the hair and ultimately change the hair's color permanently until it grows out or is cut off.

In contrast, semi-permanent hair color typically has a gentler formulation, often free of ammonia, and does not penetrate the hair shaft as deeply. It is primarily designed to coat the outside of the hair cuticle. This means it can enhance or deposit color, but it does not have the ability to lighten the hair effectively. As a result, semi-permanent color tends to fade with washing and is meant for a temporary change that can last several weeks.

The other options focus on elements that, while important in the broader context of hair color application, do not specifically highlight the key distinction regarding longevity and the ability to lighten the hair, which is the essence of the difference between these two types of hair color.