How Long To Leave Hair Dye On. The answer is simple. Any longer than that and you run the risk of serious damage including brittle strands.
If you dont want to leave it on overnight you should at least wait an hour. Im always worried that if i dye my hair and i leave it on for too long it will come out black. If you are concerned about leaving the dye in your hair for a long time you should consider an alternative solution.
If you leave it for more or less time you will probably not get the desired hair color.
The answer is simple. The hair dye takes about 30 minutes for the ammonia and peroxide to work its way into the hair cuticle to change the hairs natural pigment. Any decent hair dye requires 30 minutes for the peroxide and ammonia to work its way into the hair cuticles and change the hairs natural pigment. Leaving hair color for more than 45 minutes will cause serious damage to your hair.