Semi-permanent hair coloring washes out after six to 12 shampooing sessions. It can only darken hair or add a tone of another color to the hair. Semi-permanent hair coloring is ideal for trying out a color change to see if appeals.
Demi-permanent hair coloring lasts through 12 to 26 washings. It is excellent for touching up more permanent color jobs that are fading or for hiding a few stray grey hairs. Demi-permanent colors can slightly lighten the hair, add a different color tone or darken the hair.
Permanent hair coloring doesn't wash out at all. It grows out. About six to eight weeks after applying permanent hair coloring, the newly-grown roots of the hair in the original hair color begin to become visible.