I really like the way the Norton Synthetic Nagura cleans and prepares the surface of my GlassStones. This was recommended to me a year or so ago on a knife sharpening forum when I complained about experiencing skipping and chatter on GlassStones. The Norton Nagura really does a good job of cleaning swarf stains and prepping the surface without lapping. I scrub the GlassStones on the surface and top edges and then rinse off the slurry before each razor session.