I've been stumped with my fine (4000 grit) water stone for a while now. It gives me fits. I can occasionally get an arm shaving edge off it, but not every time. I am almost certain it has to do with how soft it is. Even the lightest passes are like trying to sharpen with chalk. A thin layer of stone material is deposited on the opposite side I'm trying to sharpen. I have only had moderate success when using an edge trailing motion, but even that isn't a guarantee. It does leave a good finish, and the shine/appearance is basically the only reason I keep it. Any tricks to get more out of it, or am I asking too much from a 4k stone (King brand)?