Stone lapping

Gentlemen, questions for the pros or advanced intermediates :)

how often does one lap his hone? After how many razors? or are there other ways to tell?

Also, I lapped my 8k on my DMT yesterday, and could never get to the corners of the stone (the grid remained). Actually, it feels as if the corners have never been flattened (different color, grittier feel). Should I have persevered? I feel that I lose a lot of stone (based on all the yellow paste washing down the drain), do I, or is it in reality negligible?

Thanks,

I my opinion, low spots on the ends are of no consequence. Low in the middle (dished) is another story. After they are flat enough (subjective) a light lapping every once in a while is sufficient. Softer water stones need lapping more often, finishers almost not at all. People shaved off of "flat" rocks hundreds of years ago and it worked fine.

I lap my hones totally flat using a grid when I get a new hone. It can take a little time to get the stone totally flat (5-10 minutes) but you want to make sure the stone really is flat, and then chamfer the edges as well.

After that I just lap them quickly before each honing session without a grid (maybe 10 figure 8's or something) and then I might lap them over the course of a honing session if the hone loads up with swarf or glazes over.

I don't count the number of razors between each lapping, it really depends on when the hone loads up.

Hope that's of some help! :)

Shaptons, Nortons, and Naniwa's are not of the same "hardness", meaning that a softer stone will dish before a hard one will. I don't own a Norton, but Shapton GS is much harder than Naniwa, thus needing lapped less often. I will "touch-up" lap after a couple settings in which I hone anywhere from 4-8 razors. Sometimes I have to spend a bit more time on them, others very little time. The grid doesn't lie & I usually use 600 grit paper, so I'm not removing much material to renew the surface. Something you should also make a mental note of is turning the stone 180 degrees to use all of the stone possible. Basically, practice & repetition will teach you what to do.