Thread: Big trouble with Naniwa Superstones 10000 and 12000

Wow - that is some serious scratching/chipping!

I have had that set of stones - the 10k and the 12k seem quite soft, so I can imagine that something could easily embed itself in the surface.

I would try lapping again. You can get DMTs from Dictum gmbh in Germany, I think. Bit pricey, though. You can get Atoma diamond plates - IMO better than DMT - from Dieter Schmid - fine-tools.com

If that is not possible, a good grade of wet-and-dry paper - not ordinary glasspaper - and pre-used at that, so that stray grains have already been dislodged. Used with copious amounts of water, the pre-used wet-and-dry paper should be OK. You might want to go higher than 600 grit, just to see if that helps solve the problem. Arris the edges on the glass mounted glasspaper, and wash down the surface of the stone with lots of water, and perhaps a nylon scrubbie.

If the stones still leave that sort of damage, they must have hard inclusions in them - a factory problem.

Regards,
Neil

If the issue is indeed contamination, my suggestion is, if you own a coticule slurry stone or some other high grit natural rub your naniwas with it and see if that changes things.

I agree with Neil, your 8k does not show any of the issues you see with your 10 and 12k, so if there is not contamination, then there must be something wrong with the hones when they were made.

Originally Posted by Neil Miller

Wow - that is some serious scratching/chipping!
I have had that set of stones - the 10k and the 12k seem quite soft, so I can imagine that something could easily embed itself in the surface.
I would try lapping again. You can get DMTs from Dictum gmbh in Germany, I think. Bit pricey, though. You can get Atoma diamond plates - IMO better than DMT - from Dieter Schmid - fine-tools.com
If that is not possible, a good grade of wet-and-dry paper - not ordinary glasspaper - and pre-used at that, so that stray grains have already been dislodged. Used with copious amounts of water, the pre-used wet-and-dry paper should be OK. You might want to go higher than 600 grit, just to see if that helps solve the problem. Arris the edges on the glass mounted glasspaper, and wash down the surface of the stone with lots of water, and perhaps a nylon scrubbie.
If the stones still leave that sort of damage, they must have hard inclusions in them - a factory problem.

I was looking for DMT and found them at DICTUM, quite pricy as You said. Dieter Schmid is a good idea, he runs his shop here in town.
As most of You guys are using these Diamont plates, I also wanted to go for them - on the other side it should be possible to go without.

I would say, I have lapped the stones about ten times by now. When I switched from Sandpaper to stone to stone I was lapping for about five or six hours (!). One of my fingers was dumb for two days after that.

I understand that contamination can occur accidentally once in a while, but I have not one single blade of eight or ten over the past four weeks that did not have one or more of these.
The 12k only has seen sandpaper once about two or three weeks ago. since then it has been lapped by 3000+ grits only and nagura.

You guys all seem to be quite satisfied and easy with those.

Originally Posted by mainaman

If the issue is indeed contamination, my suggestion is, if you own a coticule slurry stone or some other high grit natural rub your naniwas with it and see if that changes things.

I agree with Neil, your 8k does not show any of the issues you see with your 10 and 12k, so if there is not contamination, then there must be something wrong with the hones when they were made.

I only do have a nagura, that I now put aside as I was not sure if it possibly could be the source.

My 8k is lovely, it's sooo smooth and I can work on it with or without pressure. If I do circles on it, it gives me an almost mirror-shine, even under the microscope.
For the third and fourth picture of my OP, I finished on the 8k (image #3), then I rubbed this 8k against the 12k under the running faucet and then started the 12k without touching it with anything else (image # 4). If I carried grain from somewhere, I think some of it should also appear in the 5k and 8k which is not the case.

:-(

I recommend some more diagnostics with the stones. Do a few strokes on a 1-2cm lenth of stone and inspect. Then go to the next segment and repeat. See if there are zones with problematic grits. Get in there with straight strokes to find the location of problem areas, and take your magnifier to that spot on the stone to look for anomalies. I agree with others it may be an embedded grit. I've become much more light-handed with sandpaper on my stones after finding some embedded grit after several relaps.

Originally Posted by Tierdaen

I recommend some more diagnostics with the stones. Do a few strokes on a 1-2cm lenth of stone and inspect. Then go to the next segment and repeat. See if there are zones with problematic grits. Get in there with straight strokes to find the location of problem areas, and take your magnifier to that spot on the stone to look for anomalies. I agree with others it may be an embedded grit. I've become much more light-handed with sandpaper on my stones after finding some embedded grit after several relaps.

Thanks, I'll do that. I started something like that yesterday, but only by feel. Problem is, that it'll take me a razor without chips at a 5k level or so.
Maybe I'll try with japanese scraper and by this way do training in bevel-setting from "breadknife state". :-D

somehow this all can't be.. You buy stones for a few hundred bucks and need to lap half of it down the sink in order to make them usable. the 12k stone came with a rounded edge of something like 1mm. That edge is completely gone by now. Am I looking for embeded bricks ? (just talking to myself)

There must be someone in Berlin you can get together with and let them try out your stones, maybe someone who's got a diamond plate!

Originally Posted by Lemur

There must be someone in Berlin you can get together with and let them try out your stones, maybe someone who's got a diamond plate!

Would be great if someone reads it and says "hello"....

Meanwhile I got my vendors "OK" to return both stones and I spoke to "Dieter Schmid". You guys all seem to swear on the diamond plates, but they can't be the holy grail. It should be possible without. The guy from Dieter Schmid confirmed that Diamond plates also loose grit every now and then.

We can all sit here and guess what is happening however the issue you have is not common but something is causing those scratches and chips and you are spending way too much time on this. Are you sure you are not hitting the edge of the stone as you hone causing this problem?

Sounds like contamination, especially since you are using sandpaper. I would first clean your stones with cleanser and a scotch-brite pad and rinse and scrub again with the scotch-brite under running water.

Then take a straight edged kitchen knife and run the knife slowly over the stone to detect any snagging grit. A large knife may dislodge the imbedded grit. Also as recommended insure the edges are well beveled or rounded.

If you use wet and dry, (I use W/D lapping natural stones) use quality paper.

Lastly, bite the bullet and purchase a diamond plate, if you are going to hone, a diamond plate will make your life so much easier and give you consistent surface on your stones.