Thread: Definition of Hardness in Water stones & Sigma Power Stones

Originally Posted by thumbsucker

The authoritative analyses on the subject on how different sharpening mediums work is by Brent Beach whose microscopic analyses cut through much of the hearsay that gets thrown about sharpening. This tends to make Brent a little uncompromising in his views, because unlike others he can back up his statements with photos and research.

In particular you should read his finding of stropping on leather or mdf.

He also has some interesting points abut water stone slurry. Old timers say that slurry is finer broken down abrasive ground down by the action of the sharpening, and you can get a finer edge with slurry. The thing overlooked is that an abrasive not held in place by a substrate will just roll past the bevel, at best it may dent your edge but it will not remove
metal.

Interesting.

The last point on denting the edge may actually be be a burnishing effect on the edge which consolidates the edges rather than sharpening it.

I wonder whether using any compound should be with the intentions of creating a microbevel and polishing the back flat on a hard surface.

Zelk

Originally Posted by rsser

(Yes, Mt Beauty is in the next valley East of Bright).

Beautiful area, used to visit friends on a tobacco farm in Bright many moons ago.

Zelk

Haven't been to visit Brent's site in ages and found lots of new stuff there, including the section on stropping; thanks, TS.

Also noticed that he now accepts that knives require a different edge to plane blades in that they benefit from micro serrations. That's exactly why I like mist and haze (that's the micro serrations... like a micro bread knife edge) rather than mirror shiny knife bevels.

I think there is more to the slurry story than Brent asserts. A whole topic in itself for another day.

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Being a sword polisher with soon two decades on his shoulders I can tell you that when I polish my Jap tools, Kanna's, Nomi's, Gouges and whatnot I always use a slurry on the finishing stone.
When I was a beginner I did not use this method and was thus rewarded instead with a clearer window into the Kamaji or whatever lamination iron that is used. Looks pretty but the Kasumi is kept to a minimum, especially since the foundation stages were synthetic (HRC 64-67 tools) with the exception for Aoto.

In any case, I noticed a rise in edge durability and a relief while working, with the Aoto mixed in instead of a synthetic. After a quick inspection it was a light Kasumi (haze, mist, this was before I knew about serration patterns). So I produced some slurry on my finisher and really brought out the Kasumi and 'lo and behold, the edge became much more durable and keener not to mention faster to finish (you can also save up the particles from the finishing stone and use for Uraoshi on the Kanban).
This process requires -very- fine pressure and control though. With slurry on and say an Ohiira Suita which is readily available today it's very easy to overgrind the iron, so make sure your fingers are at the very edge and don't be afraid of sacrificing some skin.

I don't see much reason to put such a polished edge on a western plane though. The nature of the tool isn't meant to polish and I would much rather use a Jap replaceable HSS blade for Arashiko (somewhat in the same league).

To the guys saying slurry particles will just roll past the bevel - it's all about keeping the water level in check. The surface isn't suppose to be overflowing with water. And often woodworkers use a finishing Suita type stone which ofcourse has the "Su" (Su-nashi is basically instinct now except for a few quarries, so won't bother bringing it up), catching particles and forcing them down to smaller size granted that you don't use Nagura (a big no-no on anything past foundation stones).
The topic of natural stones could be discussed forever but I just wanted to mention that in order to produce the very finest edge, Jap woodworkers use this method.

Thanks for that post.

It got me to experiment a little with a ceramic waterstone that I've not had much joy with, and letting the volume of slurry build up and dry a little helped a lot.

..

In terms of TS's original question about what makes a stone 'hard', this may be of interest: click

rsser; Merely my pleasure to share with everyone. You get a much better result with a natural stone though since the synthetic particles in the ceramic stone are very hard to break down into smaller ones in order to create the different rows of serrations that appear on the edge with the misty appearance.

For example to name an entire kit for bringing out a very good edge. Sigma 1000&2000, Aoto (the sharpening stopped at Sigma 2000, the Aoto is a serration pattern refiner literally) -> hard and coarse Ohiira or Shoubudani Suita -> Finishing Ohiira Suita. If you want to go even further you can put the edge on a fine Nakayama Asagi and really bring out the steel but it's more cosmetic than an improvement.
That would be one of the cheapest natural alternatives depending on the stone sizes and shapes.

If you don't have the money I would say after Aoto then you will have to rely heavily on the Aoto to create the haze. That means you will have to spend quite some time on that stone and naturally flatten it very often since the Aoto is a rather soft stone (it comes in hard varieties but those are very, very rare and often have different particles).

So after the Aoto I would either use a Naniwa Jyunpaku or a Sigma 8000x. I don't see much reason bringing the edge further than that with synthetics since it will erase the haze.

All these stones are fit for any type of steel and any type of hardness, mainly tools though.
Now it's time to hit up the grinding stone again and go to work on some K120 pine fired steel

Originally Posted by Halicon

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If you don't have the money I would say after Aoto then you will have to rely heavily on the Aoto to create the haze. That means you will have to spend quite some time on that stone and naturally flatten it very often since the Aoto is a rather soft stone (it comes in hard varieties but those are very, very rare and often have different particles).

Hi Halicon

Do you have an opinion about the softness/hardness of Aoto from Tanaka Toishi Kogyosho? I have one on order via Kenneth Schwartz and would be interested in your views on that toishi.

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Tanaka? Is that a collector that went miner? I have to say I haven't even heard of it, and I have heard of pretty much all quarries that produced good stones, especially the ones around Kyoto with the "west stone" quarries that produces the best stones.

After having checked the prices he asks for, what they offer and a rough check on their quality I would say that it looks to be of the low to mid-end range. Many mislabeled stones in the purpose of earning more from the buyers. I do not dare to speak about the performance though, it has happened more than once that I have been even repulsed by a stone and later found out it polished extremely well.

You can ask the guy if the face of the stone is against the grain or with the grain. Depending on his answer he will prove if he knows anything about Jap nats or trying to sell something he has barely any idea about.
For an Aoto you have to do it along the grain, it should run straight and not horizontally like on polishing stones.

One more thing, anyone selling a Maruichi Maruka Nakayama Kiita for less than $2000 is selling a fake.
You should also watch out for newly quarried stones from the Takashima quarry. Don't bother asking why, just a heads up that will help you in the future if you go depper into the natural realm

edit: If you could ask Mr Tanaka from which quarry the Aoto was taken then I can give you a more detailed answer. Most "Toishi" (sword stones) Aoto's are on the softer side though.

edit2: Man, this is the first time I've been asked about Jap nats on a woodworking forum. This looks good! Anyone got a greenstone to spare? My euro collection of nats isn't finished without the greenstone

Originally Posted by Halicon

Tanaka? Is that a collector that went miner? I have to say I haven't even heard of it, and I have heard of pretty much all quarries that produced good stones, especially the ones around Kyoto with the "west stone" quarries that produces the best stones.

New quarry to me, too. It's just west of Mt Atago. The Tanaka family have been mining their own quarry there for six generations. So it's a traditional family toishi business. Haven't got my stone yet, so can't comment on quality. Price is about $200 for an Aoto, which sounds about right. I've been told that the stone is 'not too muddy', so perhaps will not be a very soft stone.

Originally Posted by Halicon

...it has happened more than once that I have been even repulsed by a stone and later found out it polished extremely well

Found that with my Nakayama Karasu. Initially I couldn't handle it so went on to use less demanding stones but returned to it when I had developed more skills and now it is my preferred finishing stone.

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West of Mt. Atago would make it between Atagoyama and Ohiira. I have to say I haven't the faintest what kinds of stones would be produced from that place however.

By the looks of it I would never bring a sword to the kind of stones he sells. I'm guessing that he's focusing on tool stones especially with the offerings he has.

I see that Lee Valley is now stocking Sigma Power Stones, I get the feeling that they reading these threads.

Lee Valley however are only stocking three grits, and their prices are nearly double what Stu from Tools From Japan charges.

I also see Stu now stocks 6,000 & 13,000 grit Sigmas, I will send him an email to get his thoughts on these new stones.

Originally Posted by thumbsucker

I see that Lee Valley is now stocking Sigma Power Stones, I get the feeling that they reading these threads.

Lee Valley however are only stocking three grits, and their prices are nearly double what Stu from Tools From Japan charges.

I also see Stu now stocks 6,000 & 13,000 grit Sigmas, I will send him an email to get his thoughts on these new stones.

I don't know if they read these threads, but the Sigma LV have are the Select II, for harder steels, I list both the Select II and Ceramic, and they're vastly different.

(What is ironic is that the description for the Select II at LV is a trimmed down version of what I wrote for them. Oh well...)

The pricing on the Select II is tight, I've tried to make sure that when it's all said and done, my pricing is competitive at least.

And Helmut, I'll reply here so all can read, ok?

The Sigma Ceramic #6000 is a formidable stone, it really is. Rightly aimed at the Shapton 5K as it's nearest rival, it cuts just as quickly in real terms, but stays significantly flatter, flat enough to remove any bevel rounding introduced by a coarser stone. It's one of, if not the hardest stone I've ever used. It just will not dish. It also leaves a good working, hair popping edge on tools and knives, very similar to what a Shapton 8K does.

Yes, I have one (as well as it's predecessor, a little softer) and I don't know, it's maybe on the edge of being too hard. Completely inert feeling on it, but it does work and work well. For flattening, I'd like to see something 4K from Sigma (and I'm asking them) because when there's a lot of steel on stone, it does require a lot of slurry control to prevent clogging. Only a smidge better than the Shapton 5K at resisting clogging, not enough to say "yes, it's better" with conviction.

(Perhaps slipping in the Select II 3K is a good idea here. Fast, quite flat and a moderate step for back flattening, which is useful.)

The Sigma Ceramic #13000, umm, yeah...

Completely pointless for chisels. Completely pointless for Jack planing. If you have a plane for smoothing, the steel can support the keenest edge and you are needing something that is beyond comparison, just get one now. I've not used mine very much to be honest, and I do have a lot of stones to compare to (at least 8 finish stones now), and this one completely blows my mind. Maybe the Shapton 30K is a fair comparison, but I don't know that they are as strong as the 13K is. It's hard, works as quick as you'd expect something with such fine grit to be, looks like scrambled eggs (it's called "egg colour" in Japanese) and, really it's best aimed at razor folks, because it'll leave a face shaving edge, off the stone. Passes the hanging hair test to level 2 (google it) on a chisel, which is astonishing.

If your stuck with Shapton and their grit rating system, the Sigma 13K is equivalent to a 20K Shapton.

I don't expect to sell too many of them, because they are quite expensive and quite academic. I've kinda put them into a category of "put up or shut up" because for the rather large price of admission, there's nothing else that even comes close. But it's right the way up there, and most folks really don't need the edge it can offer on their tools. In fact, the chisel I've sharpened with it scares me, and I've since 'blunted' it with a Honyama natural stone. Just plain old hair popping/end grain shaving sharp now.

Hope that helps.

It is really difficult to push the 13K because it's just so far beyond what's really useful in an edge, it's ridiculous. The 8-10K is, I think, I better day-to-day stone.

Stu, the Sigma shill.

He's been posting on his tests Helmut, here and elsewhere I think.

Added: SNAP!

Hi Stu

Thank you for the information. I am more then happy with the cutting speeds of the Sigma Ceramic stones. The Select II appeals to me in the coarser grits for hogging metal.

I am however interested in the Sigma power ceramic stone #13000 so I have sent you an order.