My natural hair color is a reddish brown and I recently dyed it black. I meant to dye it brown to get rid of the red, which I hate, but after I bought the wrong kind of dye and messed up, I colored it black to cover it and it turned out really well and actually looks really good. I dyed it about a month ago and after two weeks, had to re-dye it. After a week and a half, my hair is showing through brown again in spots. I admit, I put my hair through a lot; it's curly and I blow it dry and straighten it every day. But shouldn't permanent dye last longer than a week? I've considered having it done in a salon - but will that make it last longer? Will dying it every two weeks be that damaging? What can I do to make the dye last longer?