I knew that this would be good to cover my roots and I happened to have a coupon for a L'Oreal hair dye. Here's the results two days after coloring:
no visible roots~
I really like this hair dye because it performs well and is available at a nice price. Even though my hair isn't really an ash brown, I'm pleased that it's a medium-light brown shade that isn't brassy and looks rather natural. The only complaints I have are that it irritated my scalp a little and had a very strong, slightly tear-inducing chemical scent. Overall, good to lighten dark hair, especially dark and thick hair like mine, in one step.