Natural stones

Jason B.

Jason B.

Knifemaker / Craftsman / Service Provider
Joined
Jun 13, 2007
Messages
11,196
Can anyone tell me about the stones on this page and what the grading or grit is? And any other recommendations are welcome.
 
gosh knifenut asking for sharpening stone help!!!? this must be tricky. I cant tell anything about those stones, except that the grit probobly has something to do with the grading numbers
 
Just did a small search and this is what I found reguarding the stones from that area of Japan. This info you might already know. Doesn't seem to have a grit size. Hope this sheds a little more light. It's funny as you are my Guhru on this sort of stuff.

Historically there are three broad grades of sharpening stones. The Ara-to, or "rough stone", The Naka-to or "middle/medium stone" and the shiage-to or "finishing stone". There is a fourth type of stone which is used, but not directly. That is the nagura which is used to form a cutting slurry on the shiage-to or finishing stone which is often too hard to create the necessary slurry. Converting these names to absolute grit size is difficult as the classes are broad and natural stones have no inherent "grit number". As an indication, Ara-to is probably 500-1000 grit. The Naka-to is probably 3000-5000 grit and the Shiage-to is likely 7000-10000 grit
 
rpttrsn said:
Just did a small search and this is what I found reguarding the stones from that area of Japan. This info you might already know. Doesn't seem to have a grit size. Hope this sheds a little more light. It's funny as you are my Guhru on this sort of stuff.

Historically there are three broad grades of sharpening stones. The Ara-to, or "rough stone", The Naka-to or "middle/medium stone" and the shiage-to or "finishing stone". There is a fourth type of stone which is used, but not directly. That is the nagura which is used to form a cutting slurry on the shiage-to or finishing stone which is often too hard to create the necessary slurry. Converting these names to absolute grit size is difficult as the classes are broad and natural stones have no inherent "grit number". As an indication, Ara-to is probably 500-1000 grit. The Naka-to is probably 3000-5000 grit and the Shiage-to is likely 7000-10000 grit
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Through my google-fu I am starting to find that getting a grit # is not going to be easy. The grading is related more to the quality and cut of the stone but I get a feeling the higher the grade the better the finish.

After watching this http://www.youtube.com/watch?v=T5lmhZiup3o and a few other vid's I became interested in natural stones again (I once used arkansas stones :eek:) and started to look into natural polishing stones. The ones on the linked page are the "best" I could find without a 1-3K price tag but I can't find any reviews or user feedback so there has been a pause in purchase.
 
cotdt said:
For a high grit polishing stone, there's the Nakayama Kiita, about 25k to 45k in grit.
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A good deal on another form shows one selling for $540, that a bit out of my price range for a stone I'm not going to use much.
 
I've read a few good things about these though not natural they are more affordable.
 
Since the mines were shut down, prices have climbed, but the stones didn't really get better. They are already millions of years old, just harder to get. The high prices is many cases are not the abrasive quality alone, but size & appearance from different famous mines. I personally do not see a need for a 30 thousand dollar sharpening stone, but I was told that was within the pricing scheme for a particular mine. The vendor who mentioned it said they had a cheap one for about two grand.

It can be a crapshoot though, as stones from the same strata in the same mine can perform differently, and some can have inclusions that are detrimental to the blade's edge. Grit rating is tougher than with Arkansas stones, because Arks are solid novaculite, and abrasive quality varies with density. The japanese naturals are also quartz abrasive stones, but in a binder, so the size of the particles, how quickly they break down, and any other elements in the stone all affect the outcome with a lot of variability. You don't know how much chert, iron, etc you have in the middle of your stone until you lap your way into it. Plus dealing with cracking and sealing the edges.

I had to stop using a slurry with my kiita because I noticed it wasn't helping, but hurting my finishing efforts. That's the thing with naturals, they aren't as consistent as synthetics. Of course, that's why synthetics were developed to begin with :D
 
Well it seems as no matter how much I try to resist it I will have to settle for a quality synthetic, hardheart got any insight on the ones I have linked in post 7?
 
You may also want to take a look at these. I don't know if you frequent any of the other forums, but if you do a search, you'll find they're highly recommended.

cbw
 
Love my 10K, and I believe it was cotdt who said the 12K finished similarly but was not as soft (I have shaved a little off the face of the 10K when dealing with a deep belly) No need to soak or build a slurry, just spritz it and go. When shopping around, be sure to check for thickness, 10 or 20 mm, and whether or not it comes with a base. I got a 20mm stone with base off ebay for 70 shipped, which is pretty good.

If you want to get spendy, they have the 6K diamond hones, which in JIS is finer than the 8K DMT. But you get such good results with the DMT, you probably don't need it.

I actually have exchanged a few emails with Naniwa and got their catalogs, but I'm not in any place to make minimum orders or 20 stones for each grit I want :(

ETA- yeah the 10K Chosera is extremely well regarded. But, AFAIK, it is the same ceramic abrasive as the Super Stones, just magnesia binder instead of resin with a higher amount of abrasive overall. Supposed to hone like butter, but it needs to be soaked beforehand.
 
It looks like the Naniwa 12k super stone may Be the winner, unless I change my mind again I'll place my order in the morning. Would I need a nagura with this stone?
 
Naniwa 12k super stone is an excellent choice. The polish is a little hazy but very smooth. It doesn't need slurry, in fact better without it.
 
Choseras should be soaked 20-40 minutes, but not left submerged for extended periods, as per company instructions.
 
Choseras need soaking; Superstones can be splash and go, but the users swear they work better with soaking.

I had some Choseras and they are the best stones I've ever used, but they're way too expensive for what they do. Says the guy who's going to buy more after he refinances the homestead and saves up some spending money...
 
The fact that you were looking at natural stones is the reason I suggested the Chosera. The Naniwa SS is a hard stone that won't give much feedback (more like a Shapton GlassStone)... the Chosera otoh, not quite as hard, holds up well, but gives some feedback, and also lets you alter the conditions a bit.... create mud or a bit of slurry for different results. Thom's right, they're not cheap, but aren't as expensive compared to natural stones, (and you know what you're getting). They do recommend a soaking for about 15 min., but in a pinch can be used with just a splash of water... especially the finer stone. Both are good options... it just depends on what you're looking for.

If you haven't seen it, here's a video comparing some of the finer stones.

BTW, if you want a good primer on natural stones read "The Art of Japanese Sword Polishing".

Hey Thom, the choseras are on sale........ :eek:

cbw
 
cbwx34 said:
The fact that you were looking at natural stones is the reason I suggested the Chosera. The Naniwa SS is a hard stone that won't give much feedback (more like a Shapton GlassStone)... the Chosera otoh, not quite as hard, holds up well, but gives some feedback, and also lets you alter the conditions a bit.... create mud or a bit of slurry for different results. Thom's right, they're not cheap, but aren't as expensive compared to natural stones, (and you know what you're getting). They do recommend a soaking for about 15 min., but in a pinch can be used with just a splash of water... especially the finer stone. Both are good options... it just depends on what you're looking for.

If you haven't seen it, here's a video comparing some of the finer stones.

BTW, if you want a good primer on natural stones read "The Art of Japanese Sword Polishing".

Hey Thom, the choseras are on sale........ :eek:

cbw
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I would like to get those stones but it over budget and I would rather have the 12K. As for naturals, It was a good idea at the time but to get the quality stone I would want I would need to spend a LOT of cash....... not something I ever really plan to do unless I become a professional sword sharpener and that's not on my list of things to do.


What was I supposed to get from that video? :confused:
 
You can see, and hear (which is why the guy that made it doesn't have any other sound) a glimpse into how the stone performs and reacts with the knife. Not much I know, but sometimes every little bit helps. :)

cbw
 
cbwx34 said:
Hey Thom, the choseras are on sale........ :eek:
Click to expand...

Yep. They went from being insanely and pointlessly expensive to only being ridiculously and pointlessly overpriced. :thumbup:

And if one already has the Chosera 5K (the muddiest of the bunch), going to a Naniwa SS 10K or that magnesia-bound 10K Dave's selling is a lot more affordable for the same results.
 
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