Removed black, re-colored brown, now need to remove purple
I recently colored my hair with a permanent color that turned my hair way too black.
Based on what I read here, I removed the color with a hair color remover kit as a first step, and brought it to a color that was a bit lighter, and much redder than what I wanted to end up with. As a second step I recolored with a semi-permanent hair color that brought it quite close to the color that I was hoping for (just a bit darker) but it now has a violet undertone that is noticeable under certain light. I would not normally worry about this, but the undertone is not a natural one.
Knowing a bit about mixing color in other fields, I know that I could counteract the violet undertone by adding a yellow-ish second color on top of the existing color and hope for the best. I am worried though, that adding the second color may introduce yet another strange color in the mix, and that it may additionally take my hair to an even darker shade.
Does anyone have experience with this sort of problem? Should I try adding the yellow second color on top of the existing color and hope for the best? I do need to maintain the value (light/dark) that I have already achieved. I just need to remove the un-natural violet undertones.