Coloring Hair Again
A: The wait time depends on the condition your hair is in after it has been colored. I generally recommend that you wait a couple of weeks between chemical processes, especially if the hair has been lightened, even if the hair is in good condition.
If the hair has only had deposit-only color applied, and you want to alter the color, for example the resulting color was not dark enough in the first process, you can recolor the hair safely (again, unless there are signs of damage).
If the hair needs to be lightened to get the desired color, only perform the second color process if the hair shows no signs of damage and is in good condition.
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See also:
How to tell if you have damaged hair
After care for colored hair
The different hair color types
How often can I color my hair before I destroy it?