Naniwa220 grit lapping stone glazing

A couple of months in, the working side of my Nani 220 lapping stone has glazed a bit, and it takes a while longer to lap stuff. I'm not sure this is a bad thing -- even though the company says the 220 is good for lapping their 12K SS, it seems a little coarse for that when new. Then again, if I've got particles from the lower grit SS stones in there, I don't want to conatminate the polishing/finishing stones.

What do you guys do? Leave it alone, as a (maybe) 500 grit lapper, or lap it back to the original grit?

I use sandpaper on a slab of granite to lap any of my stones. On my 12K I usually only have to touch it up on 600grit. No more wear than a the higher grit stones (8K+), I see no need to use such a coarse stone. For the 1K, I understand using a lapping stone...I assure you that even the lapping stone needs to be lapped to ensure it's flat...

I had the same glazing issue with my Naniwa flattener. You can flatten it with a DMT, but you can't restore it with one. I ended up using 300 grit silicon carbide powder on glass to deglaze and restore it. Worked like a charm.

pcb01,

I have found the Naniwa & Norton lappers to be quite soft and frangible, and had to flatten mine quite often on 160 grit silicon carbide paper on glass.

IIRC some people had success using carbide powder in a slurry for lapping these lappers :)

Adding a drop of dish-washing detergent to the water when lapping can help keep the stone surface 'clean'.

I found the finish these lappers left on the Naniwa 12k SS was not quite good enough, so followed them with some 600 grit carbide paper on glass.

In the end I got a DMT 325 for lapping my Norton & Naniwa waterstones, and have been very pleased with the results. So much cleaner to use.

Good luck !

Have fun !

Best regards

Russ