Thursday, February 6, 2014

Waterstone dreams----- new "locals" and an old Japanese natural asagi kerasu sharpening stone?

It is the beginning of February and (Gasp!) we have snow! On the Oregon coast, go figure. This all makes makes me think of Rudy of Geological Specimen Supply, down in the California desert......

I keep going on about the ODC nagura that I use with nearly all of my sharpening stones. Yesterday I even used it with one of those India/Crystolon combo stones that I am getting from my friend Brandon and it caused such a notable change that I will be doing a separate post, just on that combo.

But for the record.....

I tried this, but it was a bit hard and my sample ended up fracturing. These are stones, after all.

The fragment worked great with this super hard chisel. That was WITH the ODC, though.

I also got a sample of welded volcanic tuff..... Interesting stuff.

Variable, pretty fast, and looks a lot like......

This is a photo from Tanaka Kiyoto and his AMAZING blog. To paraphrase, these are from different regions, but the center stone feels like tuff, while the ones on either side feel like sandstone, and the stone compare to a #400 grit. It turns out that a fair number of Japanese waterstones are volcanic tuff. Cool!

Here are some stone samples that I hope to try out in the near future....

VERY fine grain abrasive, might be too delicate?


If natural sharpening stones have one area that they do poorly in, it would be for coarse grinding. The rough stones have the reputation of dishing badly and being SLOW, SLOW, SLOW...... Is this REALLY the case? Coarse is a very relative term, but I am thinking of the #400-#1000 range. I have been using this sandstone that I grabbed off of the beach.... and the more I use it, the more I like it.

It feels very soft for a stone. Smooth, yet has a good crunchy sound, and is surprisingly resistant to dishing. About as good as my King 1200 synthetic, anyway. It IS kind of slow, but not as slow as you might think, is not muddy, but it feels like it would dissolve if you left it in the water bucket, so water control is important. I use it right after the King 1200, even though the grit is more coarse. It leaves a nice, shallow scratch pattern that is very easy to erase with the next higher grit, UNLIKE the K1200. When the weather breaks, I need to find a wider one.

Rudy has some interesting looking possibilities....

Looks like any number of coarse Jnats that I've seen.


VERY familiar looking, Kohzuke or Tajima perhaps?

LOTS of the better performing/faster Jnats are diatomaceous shale/slate.

Natural pigment!

I have been so pleased with the results that I have been getting with relatively local rocks that I start to think, "Why use Japanese naturals at all?"


Last night.......

Not much to look at and hard to tell the true color, but it appears to be a very light asagi blue. About 210-70-45mm or so.

A full skin (kawa) back, black with brown (or maybe just rust staining) and a hint of black kerasu. Kerasu stones have the reputation of being very strong sharpeners. 

45mm thick! And even! This looks like unsold merchandise from an old Japanese hardware store and may never have been lapped. Patches of kerasu?

It looks to be a very fine grain composition and when I look REALLY close, I think that I can see very slight fractures of the working surface that you will see on some really hard stones before they have been polished. Think of very slightly translucent marble, if that helps. You can also see the tell-tale marks from a 1/4 sheet sander! This seller seems to hit all of his tools with one to "freshen" them up *sigh*. It doesn't seem to hurt his sales any, he is a real nice guy, very responsive, and ships super fast!  japan-treazures 

This stone reminds me of some pictures of other stones that I've seen.... Old Nakayama storm cloud asagi kerasu, blue ghost kerasu... 

Interesting, but none of that really matters, these are just names to me. These are just dreams. What WILL be interesting is how the stone works. That is the realty. 

Next week.


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  3. Hi Jason,

    Thanks so much for this article. I read your article and ordered some stone samples from Geological Specimen Supply. I flattened the stones with sandpaper, and have used them to sharpen my chisels. I use them in this sequence - banded sandstone, shale and then slate to finish. I also ordered and use some of that ODC Nagura that you mentioned. And, let me tell you, holy smokes that is a great combination. The slate is a great finishing stone. The shale is a great cutter, and it starts to cut right away without the nagura. And, the sandstone is a pretty good cutter, too. Most of all, these things are beautiful to look at and to use. So, thanks so much for your article and blog. It has really helped me. Very much appreciated.

    1. Thanks for writing J, and sorry for not getting back to you sooner… bad.

      Rudy, at Geological Specimen Supply, was so generous with his time and knowledge, I just gotta reiterate, what a great guy! This post is 4 years old now, but he's still out there, collecting all kinds of interesting stuff…..and some of it actually works rather well for sharpening our tools! I just checked out his current offerings and I see a number of different samples of interest to me AND he still has some of the student samples of volcanic tuff, the stuff that I call ODC nagura and use in lieu of having a true Japanese Nagura stone. Now, I actually have a few true nagura stones, but I still use the volcanic ODC at times. While the ODC is variable in particle size ( a good thing, some finer than others) and as a whole are softer than true nagura, they work just fine for adding a little oomph to any hard stones that you might be using.

      The main take away from this post though, is that there actually are significant amounts of native, North American stone and mineral deposits that work quite well as sharpening stones. Japan has the history of use and the natural marine deposits that make Japanese natural sharpening stones such a pleasure to use, but we have some of the same deposits in North America as well. What we don't have is any sort of tool use and sharpening culture, not in any significant amount anyways. The searching and discovery, that's the fun part! I'm glad you enjoyed this and I'm impressed that you were curious enough to check out something a bit different.


Like all of us, I am figuring this out as I go, so when you see something that is incorrect or flat out wrong (and you will!), let me know. This is a learning process. Real people and names, please. Constructive comments and questions are very welcome, but hate speak/politics are not! Life (get one!) is too short.

Thanks, Jason