Hydrogen peroxide on its own will not completely bleach hair, but will gradually lighten it depending on how long it is left on the hair. To completely bleach hair with hydrogen peroxide, it is usually combined with ammonia in order to strip the hair shaft of its color.
For those people who want to lighten the hair, peroxide can be sprayed directly on to the hair using a spray bottle. Heat can be applied with a hair dryer to speed up the lightening process. Care should be given when using peroxide, however, because it can dry out hair and cause it to break.