Thread: J-Nat club

OK this is going to be a really arcane post, or series of posts about cutting jnat nagura from a larger stone. The first question is always ‘why would you cut up a perfectly good jnat into smaller pieces?’. Excellent question, and one that I always think about a lot before I cut one. You can make ‘em smaller, but you can’t make ‘em bigger. There are 2 reasons, one is that it’s really difficult to source razor tomo in the west. By the time that you eliminate the ones from vendors with low grit, just not fine enough, or have defects, buying razor tomo in the west has always been a non-productive excercise for me. Second reason, sometimes a stone is shaped, or has defects, such that the most efficient use of the grit is as a slurry stone. You could hone a razor on this stone for years but sooner or later, it will be tomo feed. BTW, I did hone on it several times, the best tomo come from razor-tested donors. I’m always on the lookout for suitable donor stones and found the one in the first image, stamped Nakayama, and with a shape only a mother could love, so no one wanted to bid on it. It also has a line down the middle that’s non-toxic, but if you’ve ever cracked one open you know what they are.

You can actually see two lines, the natural line (crack) that goes down the end of the stone (and all the way through), and a pencil line. The natural line is angled a bit, and the pencil line crosses it near the center of the stone. I want to use the saw cut to make the resulting tomo more rectangular/regular, so my saw cut will start to the left of the crack at the top (the notch in the top edge is caused by the crack giving way) and ending to the right of the crack near the bottom edge. So I’m hopefully going to freehand the saw down that crack and remove it.

Here’s the stone with my pencil line transferred to the back in red Sharpie, the stone will be face down on the saw table and I need a visible guide on the back. If you look closely, you can see the crack just to the left of the red line at the bottom edge/corner.

Et voilá - I did as well as I could reasonably hope for with the saw. The reddish iron lines are where the saw entered and left the crack, very little left of it. You can see the remains of the iron-filled crack in the third image, it angles up to the cut surface and appears as the reddish line/area. And finally, three shop size and one small nagura, all pure and ready for a coat of cashew lacquer. If you look at the stone in the upper right, on the top edge, you’ll see a tiny smudge of reddish color, the last remnant of that line and nothing to bother with anymore.

Just to add a footnote, here’s a tomo that’s broken along one of those familiar jnat lines.

Originally Posted by Steve56

Just to add a footnote, here’s a tomo that’s broken along one of those familiar jnat lines.

What are the the stones now tomo in your last 2 posts ? Hardness? New to jnats still learning?

Originally Posted by biglou13

What are the the stones now tomo in your last 2 posts ? Hardness? New to jnats still learning?

I don’t understand the first question. The stone that I cut is pictured. The second tomo on this page was always a tomo, I didn’t cut it. Hardness of the first set is about normal for a razor finisher, say lv 5. I don’t use the broken one on this page, it was broken when I received it.

You’ll enjoy learning about jnats, they’re very versatile. You never seem to stop learning with them, there’s always something new and interesting. Glad to help out.

With a Tomo Nagura it is not so much about hardness, it is about the grit, grit size and its frangibility. A Nagura will make slurry by the nagura breaking down, smooth the base stone face and remove a bit of grit from the base stone.

The two grits or slurry combine to make a new slurry. Often completely different from the originals from each stone, unless your Tomo is cut from the same stone. That is part of the mystique of Jnats and slurry. Add to that, slurry thickness, how or if it breaks down and technique, can have a unique effect on an edge.

Some slurries will continue to break down, refine and polish, some stop cutting and need refreshing and or a new slurry. A lot depends on the razor, technique and condition of the bevel.

Most folks have favorite Tomo nagura that work on a range of base stones but can still be tailored to produce a given result. Experimenting with different Tomo is the only way to find out what a stone is capable of. We are talking about finishing an edge, so results are varied and very subjective.

Originally Posted by Steve56

I don’t understand the first question. The stone that I cut is pictured. The second tomo on this page was always a tomo, I didn’t cut it. Hardness of the first set is about normal for a razor finisher, say lv 5. I don’t use the broken one on this page, it was broken when I received it.

You’ll enjoy learning about jnats, they’re very versatile. You never seem to stop learning with them, there’s always something new and interesting. Glad to help out.

I was inquiring about stone source or other description Ozuku, Karasu, shobudani, Kitta? My recently acquired jnat Kitta came with a tiny very hard gray tomo, it seems to raises slurry mostly from the base stone. works great for finishing. My novice opinion thinks it is an Ozuku from gray color and hardness. At this point I am researching about a larger replacement tomo.... harder than base stone / Kitta. I still learning the the qualities of the base stone and its own slurry, and not YET ready to experiment further. Hope that cleared up my questions.

Originally Posted by biglou13

I was inquiring about stone source or other description Ozuku, Karasu, shobudani, Kitta? My recently acquired jnat Kitta came with a tiny very hard gray tomo, it seems to raises slurry mostly from the base stone. works great for finishing. My novice opinion thinks it is an Ozuku from gray color and hardness. At this point I am researching about a larger replacement tomo.... harder than base stone / Kitta. I still learning the the qualities of the base stone and its own slurry, and not YET ready to experiment further. Hope that cleared up my questions.

Yes, that clears it up. I bought the stone off a Japanese auction, the description for almost all stones are the same, ‘Look at pictures, no return’. Lol.

The colors/patterns like kiita, asagi, karasu are visible so they rarely describe them except with superlatives if they’re wanting too much money. Only one or two sellers describe hardness, though several will show a bi-metal plane steel finished with the stone for sale.

I like a tomo that’s in the same hardness range as the finisher, to get a mix of both in the slurry. Mikawa nagura, the stamped white nagura used as a coarser progression are usually used on a hone that’s harder than the Mikawa nagura, the idea being to hone on the Mikawa slurry through the progression of usually botan, tenjou, mejiro, and koma. You can use a very fast tomo as a prefinisher, standing in for say the koma Mikawa nagura, even though it isn’t really fine enough to finish well.

As Marty said, you just have to try tomo nagura on each hone and see how they perform.

Looking at the broken nagura- Very interesting - I am surprised by the variability of the textures in the interior of the stone.

Adam

I can tell you from experience that matching tomo to base stone in NOT easy. I had 8 tomos for my stones(8×40$=320$) and I really only liked one(velvety smooth), you can make due but not ideal.
I purchased a Hatatoshi and made up my mind to take it to Alex Gilmore and all I can say is WOW! He knows what he is doing and has a vast collection to try and figure out which is best. If you can take it to him I would highly recommend as you get to see him at work(total pro). The second best is to send your base stone to him so he can match it up. Third would be to describe it to him and he can pick one for you. It will save you money in the end and you will have a perfectly matched Tomo for your stone. It can make your stone more versetile and speed it up. A eye opening experience for sure!