Lapping stones: to flatten your sharpening stones
Lapping stones were specifically designed to flatten sharpening stones. As you use them sharpening stones gradually become hollow in the middle. Sharpening your knife on a hollow stone using a fixed angle is nearly impossible. High time to sharpen it! After flattening it your stone will be as new again!
How do you maintain sharpening stones?
Sharpening stones need to be lapped in time, you cannot escape this fact. For it you can use diamond-coated sharpening stones, flattening stones or a levelling kit. Keep your sharpening stones in great shape!