Thread: Big trouble with Naniwa Superstones 10000 and 12000

Guys, I'm in desperate need for help, as my 10k and 12k Naniwa Superstones are giving me a hard time. They keep on to destroy my edges and I am running out of ideas what could be my fault.

I'm not sure if anyone else had these problems as I doubt the effect would be visible without a microscope or a good loupe.

I am building up my edge using 0800, 3000, 5000 and 8000. Then I would switch to 10000 to finish the job. As I had these problems with the 10k, I also bought the 12k and skipped the 10k. However the 12k is giving me the same bad results.

This is the state I end with my 8k



At the time I took the photos, I already had issues before, so I watered the 10k stone again under the fauced, checked again against the light, held my breath and did three or five very light strokes, slowly, feeling and listening to any unwanted "kr". Nothing traitorous, and still the outcome was this:




No, I did not pick the stone out of the trash bin, and I do this stuff in the kitchen, not in the workshop. And this is no single accident.

Contamination is what I thought, when these problems first occured. I used to lap all stones on a plate of glass with 600grit wet-paper and lots of water. I also used a nagura stone.

I thought, that if one of the 600grit corns would somehow stick in the surface of the stone, it might cause such a damage. So I changed my laping strategy: I now lap the 800 on the glas and sandpaper, then I lap the 3000 on the 800 (under the running faucet), the 5000 is lapped with the 3000 and so forth.
With the higer grit stones I use to prelap with the 5000 or 3000 and then also finish lapping with the stone's next smaller grit. A very tedious work.
I also abandoned the nagura, as I saw another unknown factor in that.

I tried and retried. Meanwhile stones have been laped several times. I never ever have anything like that with the 8k stone - I can do with or without pressure, x-strokes, circles - anything - lovely stone.

Yesterday I stepped from the 8k to the 12k. And it happened again

8k:


The edge was not perfect and would have done a little more work on the 3k or 5k. However the decision, which one to take was not necessary after the use of the 12k:


The 12k looks so bad now because I was angry and not willing to accept the fact and because it had thrown me back to bevel-setting on the 800 anyway. Right before I used the 12k, I lapped 8k and 12 against each other and watered the 12k generously.

How come that these stones keep on doing such a dramatic damage. What am I doing wrong or are the stones simply defect?

As this always happens after normally a few hours of careful work, this really turns me down and I'm currently kind of desperate.

Any help is gladly welcome.

Frank