Here's why:
* Semi-permanent hair color uses larger dye molecules that don't penetrate the hair shaft as deeply as permanent colors. This means the color sits on the hair's surface, fading gradually with each wash.
* Temporary hair color washes out in just one or two shampoos, while permanent hair color can last for weeks or even months.
So, if you're looking for a color that fades after a few washes, semi-permanent is your best bet.