Flattening stones is very satisfying, as the sounds changes towards the whole surface being true. I’ve got an annoying one though, that seems to be bowing out ever so slowly. I think it’s that I’m using two different grades of stone (two 1200 and one 800), and so they’re wearing at different rates. I suppose the real answer is that one should have three stones of each grade, and to only flatten like on like. Ah well. Maybe next wood show.