So I got to the hardware store today and picked up some sheets of 320 grit water resistant sanding paper. Then I spent 40 minutes on my knees in the garage, flattening the inkstone to perfection. The stone quickly produced a nice milky light grey slurry:



The result: a nice and flat stone with rounded edges:



What do you guys think? Any expert honers from Belgium around here? I'm willing to bring or ship the stone over for a test run...