# Hello! Got a stone issue, let me know where to place this request.



## Aidan (Jun 12, 2020)

Hi, I recently bought 3 Naniwa Pro stones and have an issue with them. They all, but particularly the 1000 grit seem to exude a thin rubbery glaze which balls under my thumb when I rub it. I only really noticed this after setting them to dry after use. I did not soak them, I used only s splash of water but the knife felt odd when passing it over the stone, like it wasn’t connecting part of the time, I keep clearing away the slurry. It is as if there was a protective glaze on it in the first place. After washing and standing them to dry I noticed this residue on the surface and I am bewildered. I rewashed them in cold water, no soap or solvent but the residue keeps returning. Has anyone come across this before and know any possible solution?. I am sending the 1000 grit back definitely as a small hole appeared on the surface too. But perhaps I am not used to using these stones and I am making a rookie’s error. 
Any advice gratefully received 
Aidan


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## bkultra (Jun 12, 2020)

Welcome to the forum, I'll move this to the correct section.


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## soigne_west (Jun 12, 2020)

Do you have a lapping plate or flattening stone? I found that some stones just preform better after a good lapping.


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## Aidan (Jun 12, 2020)

I used the Naniwa dressing stone but I have to say the exudate is still coming through some 5 days later.


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## esoo (Jun 12, 2020)

While I'm not an expert by any means, maybe a picture of the issue will help the more knowledgeable?


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## Aidan (Jun 12, 2020)

I have tried to take a photo but this phone can’t get it.


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## VICTOR J CREAZZI (Jun 12, 2020)

This sounds very strange. I use Naniwa Choseras (pro) in the 600, 1k, 3k, and 5k and I dont think I've experienced anything as bad as what you are reporting. The stones do seem to develop a slight glase when sitting unused, but a quick rub with that dressing stone will quickly remove it. Were the stones new when you got them? It almost sounds as if someone used a honing oil or solution on them.


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## ModRQC (Jun 12, 2020)

Was the box in which it came in good condition? That could be a clue.


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## Aidan (Jun 12, 2020)

Bought new fromknives and tools. In box as new, was wrapped in bubble wrap inside the box.


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## VICTOR J CREAZZI (Jun 12, 2020)

What is your general location? Perhaps someone with experience with the same stones could take a look. Short of that see what the seller has to say about them.


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## da_mich* (Jun 12, 2020)

This sounds strange. I have some Naniwa Chosera and SS Stones but never had this problem too. The only Chosera|Professional problem I know is the crack issue. Try a ~P240 Sandpaper at a flat surface. Maybe it will help you.


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## ModRQC (Jun 12, 2020)

@Benuser is an old-time user of these, and knowledgeable. He might chime in.


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## Benuser (Jun 12, 2020)

Not familiar to me either, this problem. With @soigne_west I would suggest serious lapping before use. 
Knivesandtools.* are very serious guys.


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## Aidan (Jun 12, 2020)

Knivesandtools.* are very serious guys.....
Well they’re not in a hurry to answer my emails


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## Nemo (Jun 12, 2020)

Never had this issue with my Choseras FWIW


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## soigne_west (Jun 12, 2020)

Aidan said:


> Knivesandtools.* are very serious guys.....
> Well they’re not in a hurry to answer my emails



There’s also a pandemic and worldwide protest going on so a little patience is your friend.


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## PotterMcMuck (Jun 12, 2020)

I have Naniwas from 400 up to 12,000 grit, some are Choseras/Professional stones and some are SuperStones. They all need to be lapped before use, as they come with some sort of protective layer on them. I don't know what the layer is made of, but they don't really work properly until that layer is gone. Don't forget to chamfer the edges while you're at it. No need to buy an expensive lapping plate, you can lap them with wet/dry sandpaper (some people say 600 grit, but I like 400 grit, personally) placed on any flat surface - glass, granite, your countertop, etc. Just be sure the surface is perfectly flat, otherwise your stones won't be flat either.


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## ModRQC (Jun 12, 2020)

Without lapping plate I used 150 for my coarse, 220 for my med, then used the med for the fine stone which mainly needed cleaning anyhow. Not a recipe of wonders. Just that sandpaper works well. 

However my atoma 140 under running water takes much faster care of any of them. It also depends on what surface you want. Coarser grit lapping vs finer grit lapping is not the same surface to start with. Muddy stones perhaps will hide the difference faster, but Shapton pros are slow to mud and the coarser/finer surface one imparts holds that much longer.


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## Aidan (Jun 13, 2020)

soigne_west said:


> There’s also a pandemic and worldwide protest going on so a little patience is your friend.


Hmmm... not so slow in taking the money, and to be fair delivery was in good time.


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## Aidan (Jun 13, 2020)

PotterMcMuck said:


> I have Naniwas from 400 up to 12,000 grit, some are Choseras/Professional stones and some are SuperStones. They all need to be lapped before use, as they come with some sort of protective layer on them. I don't know what the layer is made of, but they don't really work properly until that layer is gone. Don't forget to chamfer the edges while you're at it.


This is interesting, nobody has mentioned this before nor has any online vendor, and no instructions/ supporting information comes with the stones. But it would go some way to explaining the phenomenon


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## kayman67 (Jun 13, 2020)

I did. Also for Kramer stones and why some reviews understood nothing.


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## M1k3 (Jun 13, 2020)

It happens with Shapton stones. The top layer sucks. It works but sucks. Almost waxy. Give it a good lapping.


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## DHunter86 (Jun 13, 2020)

I never had that issue with my Chosera stones. But a seller in Japan did tell me there was a film on some of the specially made Naniwa ceramic stones they carried. So it wouldn't come as a surprised if their regular lines came with a film.


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## Aidan (Jun 13, 2020)

I don’t fully understand though. The residue continues to exude from the stone 5 or 6 days after use, I did use the dressing stone and have thoroughly cleaned and dried it since. My view is either it’s picked something up from the dressing stone or there’s a manufacturing fault


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## DHunter86 (Jun 13, 2020)

I'm not sure how much material you've expanded from the stone through use and the dressing stones. From what I've heard the pro stones wear slightly slower than the Choseras, and those wear really slowly from use in my experience. I'd reckon if it indeed was a film, you'd need to use up the first half millimeter or so to get through the film.

I'd contact the seller nonetheless just to be sure.


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## Aidan (Jun 13, 2020)

I managed to get a photo in daylight. This is the material after I have rubbed it with my thumb


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## DHunter86 (Jun 13, 2020)

I've never had that issue and hence can't be sure what it is. Though it being from a film is quite likely. 

FWIW, I've only ever had such residue from lacquer seeping onto my sharpening surface when sealing natural sharpening stones.

Similar to what the others have said, I'd try lapping off the top surface with a diamond plate or sandpaper. That flattens out the surface and might solve your problem too. 

Seeing that it affects all your stones and I'm assuming they're different grits, I'd say that it's either due to something seeping in during transport and storage, or a film put on during the manufacturing process.

Otherwise, if you'd prefer not to deal with the issue, just wait till the seller replies and maybe get them replaced.


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## Knife2meatu (Jun 13, 2020)

I must say, I'd guess that's coming either from your thumb, or something being rubbed on the stone. Maybe in drying, or in 'cleaning'.


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## Aidan (Jun 13, 2020)

Certainly not from my skin, certainly coming from the stone. After I rub it away and return later to look at it again, another fine layer has appeared particularly towards the edge of the stone away from the main sharpening area. I have only washed it in clean tepid running water.


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## mpier (Jun 13, 2020)

Aidan said:


> I managed to get a photo in daylight. This is the material after I have rubbed it with my thumb


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## ModRQC (Jun 13, 2020)

I don't know what would happen if the mixing of the bonding agent was not done correctly somehow... The way the residue curls when you rub the stone looks like the sheds of a pencil eraser used with full force. Coming out of the stone with water as it dries it stays "filmy" but as soon as you start rubbing and introducing air to the residue it takes the appearance of rubbery sediments. Or like some glues mixed with water would act. Making me think of a problem with the bonding agent. 

Don't quote me though.


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## mpier (Jun 13, 2020)

I have that same thing happen after my chosera dries. I clean mine with the dressing stone and while it is still under running water rub them down with my hand. After they dry there is always these rubbery feeling debris left on the stones, if I lightly brush them off them they feel smooth but any kind of pressure from my hand and they return which I have determined is skin and dirt from my hand. You may try brushing them off with a paint brush if the debris returns then you have other issues


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## Benuser (Jun 13, 2020)

Just to exclude a possibility: could the rubber particles I see come from a bridge?


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## VICTOR J CREAZZI (Jun 13, 2020)

I was thinking that it must be skin too, especially since you notice it more with the 1k. I realized that I had just used my 1k Chosera yesterday so it might still be a little damp and allow me to experience the same thing. The stone felt dry and had a thin residue of dried slurry on it. I got no balled up skin or anything when rubbing the stone. Possibly the dried slurry interfered. So it's still a mystery to me what is going on. My stone is the older Chosera, before being renamed Pro. 

Just tried the same with my 600 Pro and got nothing. Again there is a thin film of dried slurry on the stone.

Maybe you should leave some slurry on the stone.


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## Aidan (Jun 13, 2020)

I do use a Naniwa bridge but I don’t think that is the cause, though I follow your thinking there. Mpier reports something very similar to my issue.


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## Aidan (Jun 13, 2020)

I don’t think it’s is skin because it doesn’t happen on my King stone,


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## Knife2meatu (Jun 13, 2020)

@Aidan Do you actually have a flattening system? It's unclear from the thread whether or not you lapped the surface completely or not.


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## VicWire (Jun 13, 2020)

I have two Naniwa Pros, an 800 and a 3000. Both a couple of month old. Tried rubbing them both but nothing appears, and they do not feel strange.


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## Aidan (Jun 13, 2020)

Today I thoroughly lapped the stone on a Naniwa 220 lapping stone. Then I sharpened 4 Germans and a Tanaka. I did the Germans on the 400 and finished on the the 1000. The tanaka I started on the 1000 and finished on a 6000 king stone


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## ModRQC (Jun 13, 2020)

So it works fine now?


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## Aidan (Jun 13, 2020)

No the residue is coming through as they dry


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## M1k3 (Jun 13, 2020)

Aidan said:


> No the residue is coming through as they dry


How old are your stones?


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## ModRQC (Jun 13, 2020)

He « recently bought » them as per OP own words. Not to scold you or anything.  He has contacted seller with no answer yet is what I retain from information given.


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## Benuser (Jun 13, 2020)

Hard water?
My most recent one, a Naniwa Pro 600, is dark blue, and shows some chalky aspect after drying. I lapped only one side — I normally always use the same one. The used side shows most resistance and produces a clear tone when I go over it with my nail — nail trailing, by the way. The other feels glossy, the tone is more indistinct.


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## PotterMcMuck (Jun 13, 2020)

I've never seen or heard of anything similar, this is indeed strange. I'll be doing some sharpening this evening, I'll try and rub the stones as they dry and see what happens. If it were just one stone I'd be certain it was a strange batch of bonding agents, as someone previously suggested - but the fact that it happens on multiple stones is very bizarre.


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## Aidan (Jun 13, 2020)

Yes the fact that it’s all 3 stones, implies I have done something wrong but my king stone is fine. I’m not sure about the dressing stone


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## PotterMcMuck (Jun 14, 2020)

I tried rubbing my stones as they were drying, and nothing happened. I don't use a dressing stone, so maybe you're right about it, it definitely seems to be the only thing the stones have in common. Try using the stones without the dressing stone and see what happens, I guess!


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## turko (Jun 14, 2020)

I sharpened with my Naniwa 400 and 1k yesterday and used dressing stone, no such issues. I also tried rubbing as I had been following this thread and no issues there either.


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## VICTOR J CREAZZI (Jun 14, 2020)

This whole thing makes me want to buy a stone that I don't need to see what the heck it is, but I won't.

I guess the upshot is that the stones are still usable, so just ignore it. I use rub stones to clean my Naniwas frequently anyway. At least once per stone per session, and multiple times if I'm on a stone for an extended period of time.


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## Aidan (Jun 14, 2020)

VICTOR J CREAZZI said:


> This whole thing makes me want to buy a stone that I don't need to see what the heck it is, but I won't.
> 
> I guess the upshot is that the stones are still usable, so just ignore it. I use rub stones to clean my Naniwas frequently anyway. At least once per stone per session, and multiple times if I'm on a stone for an extended period of time.


I am beginning to feel the same way. The stones are functioning and do I really want hassle of sending these back to knives and tools ( who by the way still have not responded, which is a pity as I have put a fair bit of business their way)
However it indicates there might be a problem with the bonding which worries me.


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## VICTOR J CREAZZI (Jun 14, 2020)

Could also be that the vendor has contacted Naniwa. I expect that enough people have noticed this that at some time someone will address it.


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## Aidan (Jul 29, 2020)

So, the next chapter of this saga.
Eventually, and it took a long time- there is a train of 25 emails, KATO finally acknowledged receipt and examined the returned stones. They refunded my purchase price ( but not any thing to cover the currency conversion btw) and advised I reorder as all I wanted was a replacement. I asked for an explanation of the exudate and received this response:


*Brian* (Knivesandtools) 
Jul 23, 2020, 8:12 AM GMT+2 
Hi Aidan,

That should not be happening with Naniwa stones. Naniwa has a good reputation and these kind of problems are rare.
The top layer always is a bit more rubbery but after a few grinding actions and wettening the stone it should dissapear quickly.
It should not keep leaking rubbery substances.
Kind Regards
Brian
Warranties & Returns
KATO Group B.V.


Today I received the replacement stones. I did a quick visual check, I haven’t tried sharpening anything yet and I find two craters on the 1000grit. I am astonished.


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## soigne_west (Jul 29, 2020)

Doesn’t look to me anything to be concerned about. Give it a good lapping and proceed as usual. Stones often have little impurities from the casting process. This looks fine to me. Glad you got it worked out.


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## Aidan (Jul 29, 2020)

I am concerned. When I have bought a premium product, quite reasonably I expect premium quality, and this is the third Naniwa Professional stone I’ve bought that has a crater in it. I do not believe that at that price point I should then have to grind away at least 1 to 2 mm from the surface to make it usable.


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## Knife2meatu (Jul 29, 2020)

Aidan said:


> I do not believe that at that price point I should then have to grind away at least 1 to 2 mm from the surface to make it usable.



Good news then: You do not need to grind it away. Entirely satisfactory results are achievable irrespective of such minor surface discontinuities.


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## M1k3 (Jul 29, 2020)

You don't have to get past the holes. You'll be fine. People sharpen with large lines/cracks in stones without issue.


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## simar (Jul 29, 2020)

that residue looks like paper towel fibers left over to me


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## Aidan (Jul 29, 2020)

If I buy a natural stone then yes I expect cracks are possible but not a synthetic stone. When I first used the stone at the beginning of this thread the way I noticed the pothole was by feeling it as the knife moved over it. If I can feel it then it will mark the edge of my blade. On emailing the supplier in the first instance they responded:
Jun 24, 2020, 8:22 AM GMT+2 
Dear Aidan,

Most stones have tiny imperfections that you might see with your naked eye but wont affect your sharpening. However, the cavity on the green stone is too big, please use our return label (link) for a free return.

I share their initial view on this. A home on the face of the stone will affect the blade as it passes.
it seems to me that these stones are already showing signs of crumbling à symptom of a damaged bonding agent, which could explain the exudate I experienced with the first stones. It is entirely possible this is a faulty batch, nobody else has reported test problems before.
so I bought another Naniwa from a different site. A 600 grit, it too has a crater!






> > How can this be acceptable?


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## M1k3 (Jul 29, 2020)

I wasn't aware initially that it was also crumbling. With that also known now, it's definitely an issue.


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## kayman67 (Jul 29, 2020)

Damn. This seems beyond bad luck. Just got a new Naniwa professional 1000 recently and it's flawless, not a single issue. But you are running a bad game that never ends. Damn again. I can only imagine just how frustrating this can be. I would just cut my losses and change the game entirely.


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## Robert Lavacca (Jul 29, 2020)

I wouldn’t worry about the tiny dips in the new stones. Naniwa pro’s are great stones. I always flatten new stones myself. You’ll be fine sharpening with those tiny dips though for sure. Good on the retailer for replacing them for you. I’ve had stones show up with a corner knocked off slightly. It definitely happens.


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## Kawa (Jul 29, 2020)

You seem to have bad luck. Nothing more then that. Three times in a row? Yes, still bad luck.

Most people here don't recognize the gummy stuff coming off after a lapping or just using it.
Most people here don't have these craters. A few tiny pitholes maybe, but it should not be that bad that your knives bumps over it. It harms your edge too easily. Next to this, the crater will get bigger as you easily chip carbides out of it. You shouldn't be needing to flatten your new stone.
Totally different stone, same problem.
Normally Naniwa have great stones. My 400 pro and 600 chosera were flawless aswell

It's not a bad batch either. A batch is the same endproduct made around the same time. So they all have the exact (within tollerance of the factory) same specifications.
You are talking about 2 different problems and different stones. Unless they were drunk at Naniwa and put all parameters out of tolerance or all ingredients were out of spec...

Just 3 times bad luck.

I would skip the casino this week. Maybe even till you receive a proper stone


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## Aidan (Jul 29, 2020)

Thank you all for the amusing responses. This can’t just be bad luck. I am a little disappointed tbh.


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## Kawa (Jul 29, 2020)

Yes... it can
I hope you can see that.

I'm not going to try to convince you, other then simply this: 99% of the people here don't have the problem you are having with the same stones.
Either Naniwa has a personal vendetta with you, or.... just bad luck.



Since you said you bought from different retailers, you can also rule out that your first vendor got some kind of cheap knockoff stones or something...


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## TSF415 (Jul 29, 2020)

What exactly are you lapping and wiping the stones with?


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## Slim278 (Jul 30, 2020)

I have a set of these stones ,Naniwa Chosera, and am very happy with them. I rubbed my stones to see if I could simulate the effect and was able to do so. I, however would not consider this a bad thing. 

These are soft stones intended for fast cutting. As you sharpen a knife the abrasive materials in the stone become dull. The duller the abrasive the more friction is created until the abrasive particle is released from the binder exposing fresh, sharp abrasives. Having a binder that releases abrasives easily means you will always be sharpening on fresh abrasive equaling faster sharpening of your knife.

The forceful rubbing with your rubbery fingers is simply enough friction to rip the abrasive media from the binder in the stone.

Comparing these stones to your King stone means nothing. These are not King stones. They have different abrasive compositions and different binder compositions. They also cut much faster.


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## inferno (Jul 30, 2020)

i got all my nanipros from fine-tools.de or com or whatever it is. they were all good.


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## kayman67 (Jul 30, 2020)

__





Japanese water stones: Naniwa Professional Stones | FINE TOOLS


With its PROFESSIONAL STONE brand Naniwa offers a high-tech line of sharpening stones.



www.fine-tools.com





Yep. From here.


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## Benuser (Jul 30, 2020)

Over the years I had nine Choseras/Pros with knivesandtools.nl
With one of the 400s I found a irregularity, an inclusion. Had absolutely no impact on the sharpening. It appeared to be a wooden splinter deep of 2mm.


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## ian (Jul 30, 2020)

In what ways are the stones crumbling? Also, did you ever say what you were using to dry the stones?


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## kayman67 (Jul 30, 2020)

I got them from all over the world. No issue. The link was for this last one. 
But I understand that some have some problems. I saw some pull-out items sold as Naniwa stones, with different issues and in good numbers. I wonder just how many have such problems and at what level would the problems be considered enough not to be Passed.


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## DHunter86 (Jul 30, 2020)

My Chosera 800 came with a small crater as well, but that did not affect sharpening at all. After some use, it's gone from wear, and no new issues have arisen.

I just recently bought a Naniwa off-spec 4000 grit stone. It's was pulled from regular sales as the color was off after being in the kiln. Just received it yesterday, will report back after I've had a chance to test it.


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## Benuser (Jul 30, 2020)

DHunter86 said:


> My Chosera 800 came with a small crater as well, but that did not affect sharpening at all. After some use, it's gone from wear, and no new issues have arisen.
> 
> I just recently bought a Naniwa off-spec 4000 grit stone. It's was pulled from regular sales as the color was off after being in the kiln. Just received it yesterday, will report back after I've had a chance to test it.


A Naniwa 4k? Which series?


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## kayman67 (Jul 30, 2020)

The tool series. I forgot the exact name. But unfortunately you don't know what variation you get. They make several.


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## DHunter86 (Jul 30, 2020)

No idea, something for the domestic market I suppose, but definitely not their pro or chosera line.









*Naniwa Off Speck Item* Grit #4000 Chemical finish Whetstone w/ Base from Japan | eBay


Find many great new & used options and get the best deals for *Naniwa Off Speck Item* Grit #4000 Chemical finish Whetstone w/ Base from Japan at the best online prices at eBay! Free shipping for many products!



www.ebay.com





Bought it coz it was sufficiently cheap and had shipping weight leftover. Supposedly the mud and dish resistance is between the super stone and chosera.


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## DHunter86 (Jul 31, 2020)

Ok, found some time to test it on a Blue #2 kiridashi. Mine came in perfect condition, other than the color being off (which was expected); no craters or anything. 

The finish on the wide bevel is definitely not as fine as the Chosera 3000, and definitely muddier. But I can see this having a place in my stone collection for pre-polishing wide bevels before jumping over to Jnats. Can't say I love the "resin-like" smell from the mud though. 

Also, no residue or anything peeling off the stone after using and drying it.


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## inferno (Jul 31, 2020)

i got 99 problems but the stones aint one!


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## Aidan (Oct 20, 2021)

It’s 15 months later and the stones “bedded in”. The problem disappeared but surfaces on a Rika, must be something in the water round here! or just needed to lap /wear the stones in


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