So today I ruined my hair.....

[TootsNYC]

I guess you can't just use a lighter shade on dark hair, even just a little lighter.

I always use a "medium natural brown," and my non-gray haircolor  is nearly black. I've used an auburn as well.

I don't necessary apply anything to *lighten* it; I just apply the haircolor straight out of the box. And since it's like a stain, the gray comes out medium and the black comes out a little bit darker.

[greencat]

I guess you can't just use a lighter shade on dark hair, even just a little lighter.

I always use a "medium natural brown," and my non-gray haircolor  is nearly black. I've used an auburn as well.

I don't necessary apply anything to *lighten* it; I just apply the haircolor straight out of the box. And since it's like a stain, the gray comes out medium and the black comes out a little bit darker.

The problem is that although the stain analogy is a good one for some hair color, it doesn't take into account the fact that with box hair color, many of the lighter shades use a strong enough developer that it bleaches the hair a bit first in order to achieve the shade.  Most of the time, the side of the box will have a few before and after examples - if the box shows a before of dark brown and an after of light brown, it will bleach.