Here's the difference:
* Permanent Hair Color: Contains ammonia and peroxide, which open the hair cuticle to deposit color. It penetrates deep into the hair shaft and chemically alters the hair, resulting in long-lasting color that grows out.
* Demi-Permanent Hair Color: Contains a low volume of peroxide or no ammonia. It deposits color on the outer layer of the hair shaft and can also slightly penetrate the hair. Demi-permanent color lasts longer than semi-permanent and blends well with natural hair color, gradually fading over 24-28 washes.
* Semi-Permanent Hair Color: Does not contain ammonia or peroxide. It deposits color only on the surface of the hair shaft. Semi-permanent color washes out after several shampoos (typically 6-8 washes).
Always check the product packaging and instructions for the specific Herbal Essences hair color you are using to confirm its type and expected duration.