Hair Re-BleachingQ: I bleached my hair to get a platinum blonde color. I will need to have the roots re-bleached within a few weeks. Would it be best to re-bleach my entire head or would it be ok to re-bleach only the roots? Will the re-bleaching damage my hair?
A: Particularly when you are using a bleaching process you want to make sure NOT to overlap your color processing and restrict the application ONLY to the new growth. Bleaching the hair causes damage to the internal structure of the hair and depending on how dark your natural color is, the bleaching process can have an increased effect on the structure of the hair.
If your hair is even light brown, the length of time needed to lighten the new growth to the level needed would be sufficient to damage the previously-lightened hair irreparably. So, please do not overlap your color. This is more and more important the darker your natural color is.
If you are concerned over the potential risk of damage, do consult a salon professional for a personal assessment, and consider having your retouch done professionally. At the very least, use deep conditioning treatments before and after the retouch to try to minimize possible damage.
The bleaching process
Bleaching retouch and hair breakage