Peroxide is a chemical found in many hair dyes and is used to strip the natural or artificial color of the hair. When used in conjunction with hair dye, peroxide neutralizes the hair color so that the dye can apply a new color on top of the hair shaft. It can also be used on its own for creating highlights. Peroxide-based products must be removed from your hair in a timely fashion, otherwise it can completely strip the color of your hair until your hair is bleached.
Wash the peroxide out of your hair immediately, if you've applied it to your hair by mistake. Place your head beneath a water faucet and use warm water to rinse away the peroxide. If you rinse it out before it was able to set, it might not bleach your hair color.
Apply pigmented hair color over your hair after using peroxide on it. Peroxide is a lightening chemical, so it does not deposit color. Rather, it takes color away from the hair shaft. As such, if you wash peroxide out of your hair, but the hair color has already been lifted, you will have to add the color back to your hair with a permanent or semi-permanent hair color.
Apply the hair dye according to the manufacturer's instructions. Wear plastic gloves to protect your hands, and mix the hair dye solution in a plastic mixing bowl that you can throw away or reuse. Never reuse a plastic mixing bowl that has contained chemicals for culinary purposes.
Rinse the dye out of your hair and apply a deep conditioner. This helps keep the new color on the hair shafts and moisturizes the hair at the same time. Rinse out the conditioner.