Mixed Hair Color
A: You can NOT mix semi-permanent, demi-permanent, or permanent hair color formulas until you are ready to use them.
We can see the process occurring by watching the color of the combined “color” and “developer” mix grow darker. However, because there is a finite amount of the elements needed to create the reaction to form the color, the “reaction” will wind down once the aniline derivatives, alkalizing agents and peroxide have all combined and reacted. For most color formulas, this means that your color mixture has a lifespan of around 30 minutes from the time it is combined.
The mixture used for bleaching the hair, however, will work as long as the mixture is moist. These off the scalp bleaching powders can be “reactivated” by adding more peroxide and making the mixture moist again. (Although it’s never a good idea to simply let a bleaching mix sit out, and you cannot store a combined bleach mixture in a sealed container.)
This is why I always urge individuals to seek salon professionals before they try to bleach their hair at home. It is too easy to over-process the hair in a bleaching service.
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See also:
How to color hair
What does the developer do?
What is the ratio of hair color to cream developer?
Peroxide mixing formula
