Hair care product companies sell concentrations of the stuff (6%) in various strengths labeled 10,20,40 volume, usually with activators and conditioners to control the amount of color and minimize permanent damage to your hair. The bottle of it under your sink, usually a 3% concentration, won't do anything to your hair except damage it. Don't use the Food Grade concentration (35%) as that will damage not only your hair, but your head. 90% hydrogen peroxide is best left to the military to launch missiles.