Hair is usually lightened with bleach powder mixed with a high-volume developer, purchased from a beauty supply store for use at home, or done in a salon. Women who feel that bleach powder is too harsh on their hair can use a soap cap to achieve the same results. When used properly, a soap cap lightens the hair gradually without much damage. It's commonly used in salons to freshen and lighten hair color and fix uneven spots after bleaching.
Mix an equal amount of mild shampoo and 40 volume developer in a plastic shampoo bottle and shake well to mix it. Add a few drops of lemon juice and shake again.
Wet your hair with tepid water and apply the shampoo mix all over the hair, working it in with your fingertips.
Put a shower cap over the hair and leave the mix on for up to 30 minutes, depending on how much of a color lift you want. Check in the mirror after 15 minutes for desired lightness, and every 5 minutes after that.
Rinse out the mix after the desired time and slather on a good amount of deep conditioner. Leave it on for about 10 minutes and rinse it out with warm, then cool water. Towel-dry the hair and repeat if hair has not reached the desired lightness.