How To Redo HighlightsQ: I highlighted my daughters blond hair. The highlights have grown out and the new growth needs to be redone. How do I redo highlights?
A: The best way to re-touch highlights it using the foil method to isolate the hair that has been previously highlighted and use the color brush to add bleach (or lightening color) to the new growth.
Of course, if you prefer, you can use a frosting cap and carefully pull the previously highlighted hair through the cap to isolate it. This is however time-consuming and very difficult in many cases. You could even use a color brush to simply retouch the highlights on the top layers of the hair or where the hair "roots" are exposed, since these are the only ones that are readily visible.
Whichever method you prefer is a matter of choice. Just be sure not to overlap your color or bleach application, since this at best could cause an over-lightening in certain points along the hair length, and at worst could seriously damage the hair. Condition the hair fully before doing the retouch service, and make sure the hair is in good condition.
Foil method for highlights
Cap method for highlights
Bleaching retouch and hair breakage