No matter what I try, I cannot get rid of the copper undertones from my level 7 brown hair. I've mixed blue with my level 7 brown and the copper still comes through? I do a single process and have varied the amount of blue and I'm up to 1 to 3 portions. What am I missing, it can't be that complicated?

Sweetie, to neutralize the red/copper tones in your hair, you will need to use a green-base ash hair color. If your hair is brown, then you're a (level 4). Dark Blonde would be a level 7. Choose an ash base color that's close to your own hair color.