+22 How Long Should You Leave Hair Dye On Your Hair References. Web avoid washing your hair less than 24 hours before you dye it. Web leave the dye to sit for about 15 to 30 minutes, and then rinse out and style as usual.

The time to leave hair dye in for gray hair is as. Web the short answer. The hair dye takes about 30 minutes for the ammonia and peroxide to work their way into the hair.