Can you use a red glaze on non-red hair?

that color glaze isnt really going to change the color of your hair to much, maybe just till the next shampoo. What do you mean by "ashy" is it a greenish color ? your best bet would be to color all your hair. You can try just a semi permanent color ... if your hair is greenish ashy the red color will cancel out that greenish tone also. Find something that is a straight red that is the same level as your hair.