I use Pastel Chalks that I purchased from Micro Mark a few years ago. There were two sets, 12 each 1/4 "x 3" sticks in each set. One set was a range of greys from white to black and the other set was browns and oranges. Covers just about anything I want when weathering. Having said that, I think that any artists supply, LHS (if they carry them) or a good chain store (Hobby Lobby, Michael's etc) should be able to help you find what you want.