There are risks and dangers that go hand in hand with any kind of dye job. Regardless of whether you're just working out how to bleach hair or going from blonde to brunette, there are a number of things that can go wrong. Don’t worry though, there are steps you can take to help sort out the problem.
Don't panic if your hair is too dark for your liking: there are solutions!
It doesn't matter if you're at a salon, or are inexperienced and trying to dye your hair at home, there is still a distinct possibility that you will have dyed your hair too dark with permanent hair dye. While this might induce some panic, try to keep calm. There are a number of different steps you can take if you find that your hair dye came out too dark.
If your first response is to wash your hair once you find out your hair dye came out too dark, you'd be correct! Bleeding the color out is the optimal solution providing that you have the right product on hand. A regular or clarifying shampoo would be the best product in this situation, and ideally, you should keep washing it until enough dark dye has bled out of your hair that you're happy with the resulting hue.
After this initial frenzy of washing, it's important to keep washing your hair daily for between a week to 10 days until you're satisfied with the result and your hair is the desired shade. After this, continue a regular shampoo regimen. For optimal results use the best shampoo for dry hair you can find, and ensure that it is not for colored hair; such shampoos will attack the pigments most strongly and help ensure that your hair dye is not too dark. This works well regardless of what color hair you had previously.
The problem with having dyed your hair too dark with permanent dye and then correcting it, is that all of that excess shampooing is going to strip your hair of the vital oils it needs to protect and nourish it. These oils, called sebum, can be restored by treating your hair with nourishing leave-in conditioners as well as special masks that treat dry and damaged hair. It's going to take time to get this right, however, so don't panic if you hair isn't back to its initial splendor after one treatment.