# Uchigumori benchstone



## Badgertooth (Sep 30, 2016)

I had always wondered what uchi would be like to sharpen on so I sent a friend on a treasure hunt during his recent Japanese sojourn. Boy done good.





It's nice and big. 





It's soft as you would expect and is muddy too. The mud was an unexpected green. Most uchi I've seen is riddled with lines, this one is has some but they seem to be benevolent. 

Here you can already see what it's doing to the contrast.






I had to stop after just a few short minutes of sharpening so I've not had a chance to to even everything out but you get the idea.


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## YG420 (Sep 30, 2016)

Nice find! Looks like a nice sized stone as well.


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## Doug (Sep 30, 2016)

Nice stone, looks real clean. I have a small Uchigumori Renge that makes nice pink slurry. I even used it to get a good toothy edge on a thin ginsan petty. The softness is useful in some applications.
Appreciate all the natural stone reviews that you post. Very helpful to all of us natural toishi nuts.


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## Badgertooth (Sep 30, 2016)

Doug said:


> Nice stone, looks real clean. I have a small Uchigumori Renge that makes nice pink slurry. I even used it to get a good toothy edge on a thin ginsan petty. The softness is useful in some applications.
> Appreciate all the natural stone reviews that you post. Very helpful to all of us natural toishi nuts.



Yeah I think there's application if you're steady with your technique. I think soft stones often suffer from being recommended for beginners as if they're somehow not as good as harder stones. But really they're perfect for kitchen knives. You can undo a lot of good work by sharpening badly on really hard stones.


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## Badgertooth (Sep 30, 2016)

YG420 said:


> Nice find! Looks like a nice sized stone as well.




Dayumn, just got out the tape measure.

All 207 X 80 X 30 of her!!


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## cheflivengood (Oct 1, 2016)

Nice Find!


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## Matus (Oct 1, 2016)

The results you are getting look really cool. Please post some more once the time allows


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## aboynamedsuita (Oct 1, 2016)

I'm a big fan of your jnat reviews. Thanks for contributing to the knowledge base at KKF (and my downward spiral into natural stones lol )


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## bennyprofane (Oct 1, 2016)

Badgertooth said:


> Yeah I think there's application if you're steady with your technique. I think soft stones often suffer from being recommended for beginners as if they're somehow not as good as harder stones. But really they're perfect for kitchen knives. You can undo a lot of good work by sharpening badly on really hard stones.



This quote by Alex Gilmore was earlier posted on the German "Kochmalscharf" forum:

"Grit content and concentration and the nature of the clay binders have a lot to do with cutting action. A super hard stone that is grit rich will seem to cut slowly (unless you use a diamond plate to make a "grit rich slurry) while at the same time a grit rich softer stone will act fast cutting but the geometry of the edge can be deformed and not feel sharp. The skill of the user is also important, the ability to read the stone, to test several different stones with the steel in hand. Usually a more skilled craftsperson will feel more comfortable with a harder stone, a hobbyist with a softer stone. Like a super fast car, anyone can push down on the gas peddle but can you control the clutch, the clutch is the tricky part."

I'm not sure if he was talking specifically about razors but it's surely an interesting discussion.


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## Matus (Oct 1, 2016)

That sounds very reasonable and makes a lot of sense to me, ben and I would assume it is true for both kitchen knives than razors, the difference being that it is surely easier to cut with a so-so sharpened knife than shave with poorly sharpened razor ...


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## Badgertooth (Oct 1, 2016)

Matus said:


> That sounds very reasonable and makes a lot of sense to me, ben and I would assume it is true for both kitchen knives than razors, the difference being that it is surely easier to cut with a so-so sharpened knife than shave with poorly sharpened razor ...



Absolutely. I'm not trying to turn the convention on its head. What I'm trying to say is that if your technique is good you can get great edges on both. If your technique is bad, you'll get an acceptable edge on a soft stone and a terrible edge on a very hard stone


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## bennyprofane (Oct 1, 2016)

Than the question would be if with great technique, you can get a greater edge on a hard than on a soft stone. Wasn't trying to shoot you down, just find this a very interesting topic that I didn't know that much about. I also agree that soft stones are enjoyable.

btw, today I sharpened the first time on my super hard and very fine Nakayama Kiita and I do have to say that I haven't gotten an edge this sharp before.


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## Badgertooth (Oct 1, 2016)

bennyprofane said:


> Than the question would be if with great technique, you can get a greater edge on a hard than on a soft stone. Wasn't trying to shoot you down, just find this a very interesting topic that I didn't know that much about. I also agree that soft stones are enjoyable.
> 
> btw, today I sharpened the first time on my super hard and very fine Nakayama Kiita and I do have to say that I haven't gotten an edge this sharp before.



Haha, I didn't take it as being shot down, this is what the forum is for!! And I concur, the potential of a hard stone is larger. It is quite a shock when you experience your first ultra-refined edge off something like a Nakayama.


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## zetieum (Oct 2, 2016)

Yep, but that is the eternal discussion: I am wondering what is the point where it is too much. My experience when I get a crazy edge from stoping with 0.0000000000000000000000000001 um (or equivalent) is that the edge is scary, superb etc. But at the first prep (home user) you make: it is over and you are back to super sharp, but not crazy. I know natural stones is something else (I use them since little time). But is a super hard NAkayama not too much (pratically)? Genuine question here.

EDIT: sorry, I realise the is off topic for this thread. The Uchigumori stone looks fantastic, BTW.


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## Badgertooth (Oct 2, 2016)

A valid point and not entirely off topic. I think there's an arc of sharpness-chasing that we go through as novices - Sort of like chasing a high. We want to see how far we can take it and we assume that sharper is better. Naturally, why wouldn't you? We scoff at the advice of people who've been through the 'arc-of-extreme-sharpness' who advise us to dial it down to toothy pre-finisher levels. And then of course we experience the fleeting scary sharpness of super finishers or strops with compounds; we lose feedback on soft ingredients and realise they were probably right all along.
But it's a hell a lot of fun making your own mistakes and learning along the way. There's a great thread started a few months called 'How sharp do you keep your knives' and it posed some interesting questions and responses along these lines


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## bennyprofane (Oct 2, 2016)

Yes, that is a valid point and I will have to see how practical the Nakayama edge is, I will give an update after a few preps. I am not sure if the super stropped edge is the same, perhaps somebody else knows more. This stone was recommended to me by Watanabe for kitchen knives and he uses one himself, so perhaps they are practical. It also depends on the angle, I guess. Mr Horie from the German Japan Messer Shop did tell me once that very fine edges made with natural stones last longer than with Synth. btw I dont think I have reached that crazy level of sharpness, it does shave my arm very clean without resistance but it doesnt split hanging hair. Also, I usually dont strop on leather but on the stones. I read that with natural stones you get much less trouble with burrs.


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## Steampunk (Oct 2, 2016)

Badgertooth said:


> I think there's an arc of sharpness-chasing that we go through as novices - Sort of like chasing a high. We want to see how far we can take it and we assume that sharper is better. Naturally, why wouldn't you? We scoff at the advice of people who've been through the 'arc-of-extreme-sharpness' who advise us to dial it down to toothy pre-finisher levels. And then of course we experience the fleeting scary sharpness of super finishers or strops with compounds; we lose feedback on soft ingredients and realise they were probably right all along.



There is a great deal of personal truth for me in that statement...  I reached a peak trying to see how far I could take my edges, using natural razor finishers, high grit synths, ultra-fine stropping compounds, etc. I learned a lot and it was fun, but I began to re-think this direction when I started to realize that my super-refined edges - whilst great push-cutters - actually lost a lot of slicing performance compared to the lower grits. You can really see this when testing your edge by slicing rolled-up paper towels; the higher you go, the more sawing strokes you require to slice all the way through. This mimics what happens on soft, tough skinned fruits and vegetables. Now I'm playing around with various ways to make my edges toothier, and more aggressive, without losing too much of that ability to make a glossy push-cut through a carrot. What razor users call natural 'pre-finishers' are one of the good ways to do that... I'm also realizing that I'm actually quite happy with lower grit edges for a lot of things, and that refining the edge is really just icing on the cake at some level as long as you can de-burr the edge properly. It's interesting how things change, but that 'arc of extreme sharpness' is very real. 



bennyprofane said:


> Yes, that is a valid point and I will have to see how practical the Nakayama edge is, I will give an update after a few preps. I am not sure if the super stropped edge is the same, perhaps somebody else knows more. This stone was recommended to me by Watanabe for kitchen knives and he uses one himself, so perhaps they are practical. It also depends on the angle, I guess. Mr Horie from the German Japan Messer Shop did tell me once that very fine edges made with natural stones last longer than with Synth. btw I dont think I have reached that crazy level of sharpness, it does shave my arm very clean without resistance but it doesnt split hanging hair. Also, I usually dont strop on leather but on the stones. I read that with natural stones you get much less trouble with burrs.



I will be curious to hear your opinion after you get the chance to play with the Nakayama... 

However, in regards to abrasive-loaded strops, the type of edges they create really depends on the abrasive (Shape, hardness, volume, particle spread, etc.) and the medium they are applied to. You can have two different diamond pasted strops at the same grit level (Say, 1-micron; 12-15K JIS.); one will produce a toothier edge than a similar grit Alox synthetic water stone, the other will produce a super-smooth edge. It all depends upon the shape of those abrasives, how much their particle size varies, how your strop material holds onto the abrasive (How deeply it is absorbed, etc.), and how compliant it is. Barring both being able to get very fine, I've yet to find a strop that creates a similar edge character to a natural stone (Barring using natural stone slurry on a stropping medium, but even then the nature of those abrasives are changed by what they are applied to.). Typically, my stropped edges feel more refined and consistent like high-grit synthetic stone edges, but a little less crisp. 

In regards to natural stone edges lasting longer than synths, I would agree with Mr. Horie based upon my own experimentation... There are a lot of theories in the woodworking and knife worlds as to why this may be. Of the more logical arguments, some say that silica-based stones work harden the edge since it is a softer cutting media, some say that natural stones of all types leave less stress risers in the steel due to the nature of the abrasive, and some say that natural stones merely leave less of a micro-burr or wire edge that can cause early failure (I would debate this, as both natural and synthetic stones can result in burrs, or clean edges when viewed under a microscope; it just depends upon how much care you take.), but the only one I can conclusively see for myself [under magnification] is that natural stones have a greater variance in particle size/cutting depth than a synthetic stone of similar fineness. This creates a toothier edge than the 'grit' assigned would suggest, so the deeper random teeth left by natural stones continue to slice to some extent after the finer ones have worn down. With man-made stones featuring tighter grit tolerances, once those fine teeth are worn, the edge stops cutting completely. 

Regarding burrs on natural stones (J-Nats, Coticule's, etc. Anything that slurries. Ones that don't, like Arkansas, are a whole other matter.), my experience is that they _can_ have less burr formation than synthetics, but mostly only by virtue of (A) slurry erosion of the apex, and (B) the fact that they typically cut slower than a similar 'grit' synthetic stone. It still pays to go through some de-burring process afterwards to make sure that there isn't some vestigial micro-burr clinging on... Adding some [non-pasted] stropping into your process _might_ help you to perk your edges up a little bit more after finishing on natural stones; it depends. It typically helps mine. 

- Steampunk


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## panda (Oct 2, 2016)

when i was first starting off i always preferred softer stones. i didnt realize back then the reasoning was because they are forgiving. i've since progressed to a strong preference for harder ones because they give more accurate feedback (it tells you right away if you are cutting the bevel or if you are off)


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## Badgertooth (Oct 29, 2016)

Matus said:


> The results you are getting look really cool. Please post some more once the time allows



It took a while and I was rushing a bit, so not perfect but this is without any fingerstones or slurry on corks or any of the blending tricks. And I think I've hit a bit of a sweet, two stone progression for contrast. A heavily lapped Natsuya lays the foundation of the polish and the uchigumori refined and deepens it. Bloody hard to keep an even and consistent pressure for an even and consistent polish as you can see by the variations in the cladding.


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## Matus (Oct 30, 2016)

That looks pretty damn great. I guess that fingerstones would bring that to perfect in no time.


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## tgfencer (Nov 2, 2016)

Haha nice point Matus! Not sure I want a poorly sharpened razor at the barber, while I would not complain too much at slightly smushed tomatoes provided I still had a throat to eat them with...
Nice photo by the way, OP.


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## Krassi (Nov 23, 2016)

Hiho.

Wow looks damned good Badgertooth!
I also have my new brick size Ohira Uchigumori lying around and waiting to polish a lot of my knifes.
Had my karoshi work weeks with to many work but now its relax time and test all the new stones.

Its amazing how fast you get a super sick Kasumi finish and its also giving a nice edge and the slurry is killer for polishing.
ill post stuff once a knife looks fancy 

Seeya,daniel


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