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

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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.
 
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
 
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.
 
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.
 
I don’t think it’s is skin because it doesn’t happen on my King stone,
 
@Aidan Do you actually have a flattening system? It's unclear from the thread whether or not you lapped the surface completely or not.
 
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.
 
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
 
No the residue is coming through as they dry
 
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.
 
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.
 
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.
 
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
 
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!
 
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.
 
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.
 
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.
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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.
 
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.
 
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.
CDE87862-C508-455A-85B8-2200B299BDFE.jpeg
 
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.
 
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.
 
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!
463A47C6-C80F-435D-99E2-685B3FE2940B.jpeg

How can this be acceptable?

Click to expand...
Click to expand...
 
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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