Can Shapton stones be flatened with sandpaper on glass the way regular waterstones can?
The short answer is yes, they can be flattened with that method. There are some issues though. #400 grit seems to be the limit of the paper before it begins to clog. The engineers at Shapton want a smooth reflective surface on the stones from the #5000 up to the #30000. The fine grit powder that Shapton manufactures for the lapping plate is about #4000 grit. The best performance from the stone is realized when it is very flat and smooth. It will stay flat much longer this way because the cutting particles are supported by neighboring particles. If the surface is rough, the particles at the top of the ridges will come away very easily.
