Why is my sharpening stone disintegrating?!

[OkayMode]

I bought a JNS 1000 Matukusuyama a year ago and was quickly impressed with it.

It was on the harder side, with good feedback, slowish loading, fast, and good for both edge sharpening and polishing.

Recently though it has become unusably soft, crumbly, and friable, and I have no idea why. Edge sharpening is no longer possible as it’s impossible not to dig into the surface of the stone (which nearly cost me a tip yesterday), and bevel sharpening isn’t viable either if you want a remotely clean shinogi.

I’m at a loss; the colour has darkened a bit over time, which combined with the softening suggests it has been waterlogged, but I’ve never soaked it ever and always dried it out for at least 24 hours before putting it away like with all my stones.

I’m not even holding the stone in the attached video - that’s how easy it is to gouge it currently.

What has happened here?

 

[NickMinton]

Anything to suggest storage in a humid setting?

 

[OkayMode]

Anything to suggest storage in a humid setting?

There’s no moisture, smell, mould etc in the box it’s stored in…

I’ve currently got it hanging out in the conservatory in full sun for a few days to see what happens.

 

[Cliff]

I don't think full sun is a good idea. Is this one of the Resinoid stones? If so, the key is to dry slowly. It may be counter-intuitive, but wrapping it in a towel for a while may help keep it from cracking as it dries. As I understand it, the issue is that when they absorb water, they don't dry out at a uniform rate. That is when you run into problems.

 

[esoo]

Maybe @maxim can comment?

 

[OkayMode]

I don't think full sun is a good idea. Is this one of the Resinoid stones? If so, the key is to dry slowly. It may be counter-intuitive, but wrapping it in a towel for a while may help keep it from cracking as it dries. As I understand it, the issue is that when they absorb water, they don't dry out at a uniform rate. That is when you run into problems.

I’ve put it naked in a warm cupboard instead, fingers crossed something happens - I’m not convinced it is still damp but will check how it’s doing in a week or so.

 

[cotedupy]

Ah yeah, classic… over time Fluoride in the water makes stones very crumbly. And also Communist.

Not much you can do now unfortunately. Just don’t give it a beret and an AK-47, otherwise your conservatory’s gonna get f***ed.

 

[ethompson]

Ah yeah, classic… over time Fluoride in the water makes stones very crumbly. And also Communist.

Not much you can do now unfortunately. Just don’t give it a beret and an AK-47, otherwise your conservatory’s gonna get f***ed.

Only thing sharper than your knives is your wit

 

[OkayMode]

Ah yeah, classic… over time Fluoride in the water makes stones very crumbly. And also Communist.

Not much you can do now unfortunately. Just don’t give it a beret and an AK-47, otherwise your conservatory’s gonna get f***ed.

Just walked in to this… should I be concerned??

Luckily I keep my harder political literature under lock and key.

Is it salvageable @cotedupy or should I be taking recommendations for a 1k replacement? And how come it has only knackered this stone and no others?

 

[aporigine]

Just walked in to this… should I be concerned??

Luckily I keep my harder political literature under lock and key.

Is it salvageable @cotedupy or should I be taking recommendations for a 1k replacement? And how come it has only knackered this stone and no others?

I too have a political-containment policy.
But I swear those red label guys are busy at night whispering **** at my stones of all grits and persuasions to “make abrasives great again.” Some of my best hocho are developing right-biased grinds, and I’m at wit’s end trying to bring them back to a more liberal geometry.

 

[cotedupy]

Just walked in to this… should I be concerned??

Luckily I keep my harder political literature under lock and key.

Is it salvageable @cotedupy or should I be taking recommendations for a 1k replacement? And how come it has only knackered this stone and no others?

Superb!

 

[bill_zeng]

Just walked in to this… should I be concerned??

Luckily I keep my harder political literature under lock and key.

Is it salvageable @cotedupy or should I be taking recommendations for a 1k replacement? And how come it has only knackered this stone and no others?

I don't know what happened to your stone, but I wanted to say that I really like that steel frame road bike in the background.

 

[cotedupy]

Just walked in to this… should I be concerned??

Luckily I keep my harder political literature under lock and key.

Is it salvageable @cotedupy or should I be taking recommendations for a 1k replacement? And how come it has only knackered this stone and no others?

I mean look at what the Fluoride did to my Coticule Wheele. You can’t tear him away from this stuff now. He’s completely engrossed.

 

[aporigine]

I mean look at what the Fluoride did to my Coticule Wheele. You can’t tear him away from this stuff now. He’s completely engrossed.

View attachment 337305

Just you wait til he’s all in in “Das Shapital” and “Stalin and the Atoma.”

 

[Up_dog128]

I just went into my shop to find the Naniwa and Shapton have flown a banner that reads "Unite the Pro-letariat!"

 

[aporigine]

I just went into my shop to find the Naniwa and Shapton have flown a banner that reads "Unite the Pro-letariat!"

The only Chosera for a bright, liberated future!

 

[Legion74]

Is it salvageable @cotedupy or should I be taking recommendations for a 1k replacement? And how come it has only knackered this stone and no others?

Because all hones are created equal, but some hones are more equal than others.

 

[mengwong]

If the stone’s resin is acting as a venue for ion exchange chemistry, would it be possible to recharge it with a soak in NaCl or NaOH?

https://www.seplite.com/sunresin-ion-exchange-resin/

I don’t actually know anything about this beyond once putting salt in my dishwasher.

 

[mengwong]

TIL fluoride can attack the aluminum oxide of the stone itself

https://en.wikipedia.org/wiki/Activated_alumina

 

[aporigine]

If the stone’s resin is acting as a venue for ion exchange chemistry, would it be possible to recharge it with a soak in NaCl or NaOH?

https://www.seplite.com/sunresin-ion-exchange-resin/

I don’t actually know anything about this beyond once putting salt in my dishwasher.

I’d steer clear of alkali on general principles. It eats things.

 

[aporigine]

TIL fluoride can attack the aluminum oxide of the stone itself

https://en.wikipedia.org/wiki/Activated_alumina

Activated alumina is very different from the abrasive stuff.
Also, sorption of fluoride requires somewhat acidic pH since the reaction is much better for HF than for fluoride ion.
That said, the threat of Communism is pH-independent.

 

[Nemo]

When I read the title of this thread, I was sure it was going to be about a Cerax 300.

 

[OkayMode]

Well this thread went completely off the rails (albeit in quite an entertaining way) very quickly…

Any more insights on what’s happened here and whether I can fix it greatly appreciated!

I don't know what happened to your stone, but I wanted to say that I really like that steel frame road bike in the background.

Good spot. People laugh that it’s pink until I overtake them

 

[cotedupy]

Well this thread went completely off the rails (albeit in quite an entertaining way) very quickly…

Yes apologies for that mate, you got me in a somewhat irreverent mood last night. Though tbh your response was so good that it probably deserved its own thread... Pictures of Stones Caught Reading Left-Wing Literature.

And frankly you should've seen it coming: JNS RED Aoto...?! The place is hotbed of Marxist whetstone ideology.

 

[Jovidah]

Perfect for sharpening your Takamura R2 Migaki... I always knew there was something fishy about it.

 

[Heckel7302]

Well this thread went completely off the rails (albeit in quite an entertaining way) very quickly…

Any more insights on what’s happened here and whether I can fix it greatly appreciated!


Good spot. People laugh that it’s pink until I overtake them

Steel frames are awesome. This 40 year old Panasonic DX-3000 still runs like a champ

No idea about why your stone is falling apart on you, sorry to say.

 

[stringer]

Well this thread went completely off the rails (albeit in quite an entertaining way) very quickly…

Any more insights on what’s happened here and whether I can fix it greatly appreciated!


Good spot. People laugh that it’s pink until I overtake them

It could be that your skin is too acidic for the stone. Try eating some baking soda half an hour before your next sharpening session.