In haircoloring, what is the difference between semi-permanent and permanent color?

In hair coloring, semi-permanent colors are distinct from permanent colors primarily due to their formulation and longevity on the hair. Semi-permanent colors do not contain ammonia, which means they are less damaging to the hair and typically last for a limited number of shampoos, often around 4 to 12 washes, depending on the product and hair care routine. This temporary nature makes semi-permanent colors ideal for those looking to experiment with hair color without the long-term commitment.

Additionally, semi-permanent colors deposit color onto the hair shaft but do not penetrate the hair cortex like permanent colors do. This lack of penetration is why they gradually wash out over time. On the other hand, permanent colors typically contain ammonia and/or other chemicals that allow them to permanently alter the hair's natural color by opening the hair cuticle and depositing color deep within. As a result, permanent colors provide longer-lasting results.

The distinction between the two types of hair color is crucial for stylists and clients to understand when deciding on a hair coloring service, especially in terms of desired longevity, maintenance, and hair health.