Cleaning oil stones with penetrating oil and cardboard - GIF

[piper184]

I usually just spray the WD on the stone and wipe with a cloth. Will have to try this "one weird trick"

[Philip Davies]

I usually just spray the WD on the stone and wipe with a cloth. Will have to try this "one weird trick"

Water and paving slab slurry. Or, better, abrasive grit on plate glass. Oh, and elbow grease. A horizontal grinder is speedy. I have flattened a stonusing an abrasive wheel chucked in a bench drill.