Touching up your hair color as your roots grow out is a daunting task to undertake at home. If you miss spots, they will show. If you overlap fresh bleach onto previously bleached hair, the hair could turn white or break off in the overlapped areas. However, if you love the low price of being a do-it-yourself bleached blonde, you may be willing to take the risks involved with bleaching roots. Just remember, bleaching mishaps can be extremely costly if you have to go to a stylist to have them repaired.
Find a trusted friend or family member who has experience coloring hair to be your assistant. Trying to touch up your own roots is extremely difficult, because it's hard to see and reach the roots at the back of your head.
Put on your salon gloves, and have your assistant put on gloves as well.
Mix the powdered bleach and peroxide in a plastic bowl following the instructions that come with the bleach. Volume 20 peroxide is suggested if you have naturally light hair, while volume 30 or stronger is meant for darker roots. Use a plastic spoon to mix the bleach into the peroxide until it is completely dissolved.
Brush out your hair until there aren't any tangles. Section your hair into six even sections, and secure the sections with hair clips.
Have your assistant dip the small bleach applicator brush into the bleach mix and use it to cover only the roots, one section at a time. Only apply a small amount of bleach at a time to avoid bleach running or smearing.
Leave bleach in hair until the roots look as if they have lightened enough to match the rest of the hair.
Wash bleach out of hair using shampoo and conditioner. Towel-dry your hair.
Apply violet or blue-violet toner at the roots. Wait about one minute, and then apply it to the rest of your hair to get an even tone and remove brassiness. Leave in toner only as long as you need to. Watch your hair as it processes until it looks neutral. If you leave toner in too long, your hair can turn purple.
Wash out toner using shampoo and conditioner. Style hair as usual.