# Is this typical for a real Asano nagura?



## PalmRoyale (Dec 13, 2017)

My father in law stopped by at my job this morning to give me a present, a 213 gram chunk of Asano koma nagura. The slurry from this nagura is completely different from the unmarked koma nagura I bought from Shinichi Watanabe. It's almost like sharpening on whipped cream before it's whipped and the slurry lubricates my suita extremely well. Is this kind of slurry typical for a genuine Asano nagura?


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## tripleq (Dec 13, 2017)

This is very tough to say. Like any natural they are all different and there are many hardnesses and grades of Asano nagura but it does not sound outside the realm of possibility. What is the difference in colour between the two?


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## PalmRoyale (Dec 13, 2017)

The koma from Shinichi is like a dirty white with some iron in it, this new one is a pure white with some yellow spots. They seem to be about the same hardness but it's much easier to make a slurry with this Asano nagura. Here are 2 pics.


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## tripleq (Dec 13, 2017)

It looks ok. The pic (2nd) appears to be one of the finer/more pure nagura - probably a Koma (can't really read anything on my phone) BUT you never know. There are so many fakes around in the natural world (even nagura). Try a shave test (I'm assuming you're straight sharpening - if not, sorry) and compare it with the stone from Sin. That might give you a better idea of what you have. If it isn't too indelicate you might ask where he got the stone from.


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## K813zra (Dec 13, 2017)

I have found the Asano nagura that I have used to have a creamy but chalky mud that is colloidal. Not sticky, thick swampy mud like I get from some other naturals. I have only used a few of each grade but none were 100% the same.


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## PalmRoyale (Dec 13, 2017)

It has a koma stamp so it's safe to say it's a koma. My father in law bought it from Japan messer shop in Germany. If you look at what they carry it seems to be a trustworthy shop so I think this is a genuine Asano.

Edit: creamy and chalky, that's exactly the slurry from this stone. It dries to a fine chalky powder.


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## ob-gym (Dec 13, 2017)

"Koma" is an approximate grit rating, not where the nagura is from. Neither is Asano, which refers to the red stamp which says "Checked by Asano", it's an old indicator of quality, but there are tons of fakes.

The one you just got says "Pure Mikawa White Nagura" and it looks exactly like the Mikawa nagura I got from K&S, the slurry is chalky and very smooth. The one from Watanabe may be fine grit (Koma) but doesn't look like Mikawa nagura to me, which is a specific type of nagura.


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## PalmRoyale (Dec 13, 2017)

When I say koma I mean how fine the stone is, I know it's from Mikawa. Btw the description on the product page is "Mikawa Shiro Nagura Koma K111", not "Pure Mikawa White Nagura". And when I say Asano I mean it has the Asano stamp. I'm not a complete buffoon. Anyway, it doesn't really matter if it's really checked by Asano or not. It performs beautifully and in the end that's all that matters. It's a great gift and I love the end result with this nagura.

And to be clear, Watanabe never said it's a Mikawa nagura. He just listed it as shiro koma.


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## alex1921 (Dec 13, 2017)

Hi, I am a razor guy that occasionally buys stones here. The Koma in the bottom picture is a Betsu Jou, white odd shape. &#21029;&#19978;. Some koma can feel more grainy and others are more creamy. The shape is not uncommon for koma, it's hand cut. Of course without testing it, inspecting under microscope etc one cant be 100% sure but AFAIK it looks legit to me.


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## Badgertooth (Dec 14, 2017)

PalmRoyale said:


> I'm not a complete buffoon.



Then don't ask questions about typicity and get defensive about a perfectly reasonable answer.


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## brooksie967 (Dec 14, 2017)

So, here's the breakdown in "layers" from the mikawa nagura mine:


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## PalmRoyale (Dec 15, 2017)

I would have thought koma and mejiro would be close together and botan and tenjyou as well.

Btw, I discovered a koma nagura slurry is an excellent lubricant for my Sigma Select II 6K stone. I use it to hone my PM-V11 and A2 plane blades and the slurry makes it so much easier.


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## Framingchisel (Dec 15, 2017)

Very helpful to see the core sample of the strata.


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## K813zra (Dec 15, 2017)

PalmRoyale said:


> I would have thought koma and mejiro would be close together and botan and tenjyou as well.
> 
> Btw, I discovered a koma nagura slurry is an excellent lubricant for my Sigma Select II 6K stone. I use it to hone my PM-V11 and A2 plane blades and the slurry makes it so much easier.



Yep, me too. To be honest I don't notice much of a difference between my 4 piece nagura set when it comes to the edge quality. Maybe if I was shaving off of the edge like the razor guys do then I would.


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## PalmRoyale (Dec 15, 2017)

Do you notice a difference in speed between botan and koma?


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## K813zra (Dec 15, 2017)

PalmRoyale said:


> Do you notice a difference in speed between botan and koma?



That is a tough question but I would say, on a knife, realistically no. Maybe a stroke or two per pass if I were to count. But I just use them to make slurry on harder stones. In my case, I use most of my Nagura on a very hard Aizu (hard for a naka-to) so the base hone itself might actually cut faster than the nagura itself. I don't use much by the way of Awase-to and what I do have does not need nagura so it is hard for me to make a fair guess. I suppose I need a piece of slate or something that is very low in abrasive property to test them fairly.


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## PalmRoyale (Dec 15, 2017)

Here's something interesting I read some time ago in a thread on reddit:



> also, just to correct any misunderstandings. it is not the slurry that makes a stone cut. slurries, when left on the stone promote what is called "free body abrasion" which actually slows down cutting.
> 
> the reason slurries are known to increase cutting speed is because the fact that they form, means that fresh abrasive is being exposed. so for maximum cutting speed, you would want to continually rinse the stone to keep the free body abrasion to a minimum.



I don't know anything about the science behind sharpening but it does seem to me the koma slurry on my suita does a lot of the cutting. It's especially noticeable when I polish the back of a chisel. In that case there's a slurry layer between the steel and the stone and metal is still being removed.


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## K813zra (Dec 15, 2017)

PalmRoyale said:


> Here's something interesting I read some time ago in a thread on reddit:
> 
> 
> 
> I don't know anything about the science behind sharpening but it does seem to me the koma slurry on my suita does a lot of the cutting. It's especially noticeable when I polish the back of a chisel. In that case there's a slurry layer between the steel and the stone and metal is still being removed.



Yeah, I am totally not a science type. :biggrin:


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## PalmRoyale (Dec 16, 2017)

So what this guy meant was two-body vs three-body-abrasion. With two-body-abrasion there's a fixed abrasive, the stone, and you continually have to rinse it so avoid the build up of mud so the steel is always in full contact with the abrasive for the most aggressive sharpening action. With three-body-abrasion there's a free floating abrasive on the surface of the stone, a slurry or mud, and the abrasive particles are free to roll around under the steel for the most aggressive sharpening action. There's no general consensus among scientists and engineers which is better but using a nagura slurry on my suita I can say from experience, and I think a lot of others can as well, that three-body-abrasion is more aggressive.

Btw, another nagura, this one is from the Mejiro stratum. It was just 30 (50 with shipping so I just took a chance) on Yahoo auctions for 237 grams and it's superb. Soft and very easy to make a slurry with it and fast cutting. I don't know if it's really checked by Asano but it works so well that I don't care.


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## K813zra (Dec 16, 2017)

PalmRoyale said:


> So what this guy meant was two-body vs three-body-abrasion. With two-body-abrasion there's a fixed abrasive, the stone, and you continually have to rinse it so avoid the build up of mud so the steel is always in full contact with the abrasive for the most aggressive sharpening action. With three-body-abrasion there's a free floating abrasive on the surface of the stone, a slurry or mud, and the abrasive particles are free to roll around under the steel for the most aggressive sharpening action. There's no general consensus among scientists and engineers which is better but using a nagura slurry on my suita I can say from experience, and I think a lot of others can as well, that three-body-abrasion is more aggressive.
> 
> Btw, another nagura, this one is from the Mejiro stratum. It was just 30 (50 with shipping so I just took a chance) on Yahoo auctions for 237 grams and it's superb. Soft and very easy to make a slurry with it and fast cutting. I don't know if it's really checked by Asano but it works so well that I don't care.



I know that with some of my stones if I do not raise a slurry I can try to sharpen for half and hour and more or less nothing happens. A very hard binsui, for example. However, if I hit it with a diamond plate the thing comes to life and strips metal from the knife like a demon. Now, if I use some other sort of nagura rather than a diamond it does not seem to raise any slurry from the binsui itself and it cuts much, much differently. For my uses, that is enough proof of how things work. I don't see this as a set thing because different stones react differently.

I'm a farmer not a scientist though. :biggrin:


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