Thread: How does Lapping actually work?

To answer the original question (or attempt to):

Yes, 250/400 grit sandpaper will leave scratches on your hone. Don't panic though, the finish off of 400 grit paper is fine. I used 400 grit paper to finish my hones for a while.

So you get the flat part, that's good. But what else does lapping do? For one it cleans the hone. IME, plenty of swarf builds up, esp on the finer hones.

IMO lapping controls the texture of the surface, and thus its level of aggression. Heres what I think:

After lapping, the hone's surface is covered with ridges and valleys left by the grit of your lapping plate. The razor edge contacts only the peaks on a freshly lapped hone, and exerts more pressure on each contact point than if it were making contact all over the edge. The ridges wear quickly and make fast cutting slurry. New cutting material is constantly exposed. Swarf collects in the valleys. After a while the peaks and valleys left by your lapping plate, will wear down. The hone smooths and begins to act finer and slower. The razor is exposing less material and swarf begins to clog the stone. Re lapping the surface, preps your hone with new peaks and valleys and the hone gets more aggressive again.

When I lap with the Norton plate I see the above in action. My stones are definately more "ready to work" right after lapping. After a while they do slow down, and polish finer. On the 8k, I even see a yellow slurry form after the first, no pressure strokes and the stone seems very quick cutting. I don't think the stone works as well after lot's of use without lapping.

With luck, some of this made sense.

Michael