What if I dyed my already dyed black hair light brown?

I want my hair to look dark brown. also if i bought like 3 boxes of light brown dye, would my hair come out brown?What if I dyed my already dyed black hair light brown?
Wouldn't work. The only way it would work is if your black hair was natural and you used 40 volume. But it's not, So you need bleach.What if I dyed my already dyed black hair light brown?
You need to bleach out the black first, and then once the bleach is rinsed out and your hair is dry, you can color it brown. Also, a good idea would be to go to your local beauty supply and ask someone who works there what products they recommend.....You should also buy some cholesterol, because I've stripped color out of my hair, and it REALLY dries it out.