Color over Dyed Hair

Bowl with hair dye
Photo: Photopixel/Shutterstock
Q: I recently dyed my hair black/dark brown and was told I can't dye over it again. I have to wait until it grows out. Is this true when I only want to dye it the same color or a shade darker again?
 
A: If you've used a standard hair color brand (purchased from a beauty supply and mixed with developer) and you only want to go the same color or a shade darker, you absolutely do not have to wait for it to grow out.
 
As long as your hair is in healthy, undamaged condition from the previous process, you can feel free to safely color over it. Just be sure to use the same base color tone in the new formula as you did in the original to avoid any unwanted color conflict problems.
 
You do still have to be cautious with certain alternative types of hair color (henna-based and metallic salt hair colors, for example), as these can react terribly with regular chemical color mixes and cause severe hair breakage.
 
Now, if you were told by a salon professional that you have to let the hair color "grow out," you need to understand the reason you were told this. I'm guessing that you weren't told this by a pro, because he or she should have explained the mechanics behind it. A stylist usually warns you about this because of a golden rule in hairdressing: color cannot lift color.
 
While you can easily go darker, you cannot use regular hair dye to lighten hair that has already been artificially colored. If you try to put a lighter brown dye over your current dark dye, it will do absolutely nothing to the dark hair, but it will turn your natural, virgin root regrowth a bright, brassy shade.
 
To lighten previously colored dark hair, you cannot use standard tint; you have to use bleach or a professional color remover, which should be done with extreme caution to avoid severe damage and unpleasant results.
 
If you really are just sticking to the same dark color or going darker, you are perfectly fine to proceed. Just keep color buildup in mind. If you pull permanent dark dye all the way through to your ends every single time you color, the hair will become oversaturated. Over time, this makes the ends look dull, dry, and an unnaturally flat, inky black.
 
To keep your hair healthy, try applying the permanent dye only to your new root growth. If the rest of your hair needs a refresh, use a gentle, deposit-only demi-permanent color or a color gloss on the faded ends for just the last few minutes of your processing time.
 
©hairfinder.com
 
See also:
 
How to color hair
 
Damage caused by hair color
 
Hair color removers for henna and black tints
 
How hair coloring can damage your hair