Each hair mask has a different purpose, but typically hair masks are designed to repair REALLY damaged hair (like after someone bleaches their hair for example, it will be very dry, brittle, and damaged). Hair masks can restore hair to it's former health and shininess. put it through your hair when your hair is wet (like once you come out of the shower), and leave it on from anywhere from 5 to 30 minutes. I like to put a plastic shower cap over my hair when I use a hair mask.