Stone ID: Tsushima?

[GorillaGrunt]

I’ve been getting into inexpensive sharpening stones lately as I’ve given up on polishing and the sort of stuff that requires expensive jnats. I got this stone a couple years ago, bought it on EBay or something as a Japanese stone with no other identification as to mine, layer, etc. I’ve been looking at a bench size Tsushima and it finally occurred to me that this looks kinda like one.

It’s hard and very fine; diamond or sandpaper will raise a little slurry but for knives it’s best with a nagura, kind of like a Roszsutec or something. It’s pretty grabby but not sticky-suctiony. It is completely homogeneous without veins or patterns or dots. I’m pretty sure it is actually Japanese and not like a slate from somewhere else; the feel of it is right for a jnat.

I have a nagura size Tsushima that I’ve posed next to this one for comparison. The stone in question is a uniform very dark gray, maybe slightly greenish; I’m not convinced it’s black enough to be the black one or blue enough to be the blue one. To the touch the two stones do feel rather alike. The slurry color is, like the stone color, close but slightly different compared to the known Tsushima.

I‘m not so much in need of identifying exactly what it is, although if someone can do so easily then fantastic. I’m more trying to determine whether or not I already have a bench size Tsushima before buying (another?) one.

thanks!

 

[Rangen]

This business of identifying JNats from pictures is tricky. Part of me was prepared to say "sure, that's a Tsushima," but then I thought about it.

You say it is "hard and very fine; diamond or sandpaper will raise a little slurry but for knives it’s best with a nagura." That resembles my Tsushima not at all. My Tsushima yields copious slurry with a small number of strokes of a played-out diamond plate. I would never describe it as "hard." I'd describe it as "kind of soft and slightly muddy, but not nearly as muddy as an Aoto." And the more I look at the resemblance, the less of a match it seems.

Tsushima - Wet


Tsushima - Dry

You know what it reminds me more of? This remarkable hard Aoto I bought here on the BST. Aotos are soft and muddy, but this one is the opposite. I think there is a name for this kind of Aoto. I don't remember it, but I think it begins with Z.

This Aoto is extremely hard, and yields slurry only very reluctantly to a diamond plate. Its grit is very suitable for razor finishing. I have shaved with a razor that was finish-honed on it, and have no complaints. Any chance that yours is like this one?

 

[GorillaGrunt]

Could very well be! I only have one Aoto and it’s soft, muddy, thirsty, and more of like a 3k-4k grit if I had to guess, but I know they come in a lot of flavors and mine was the cheapest of three grades offered when I bought it. The grit and hardness/slurry formation does though, now that I’m messing around with it, match pretty well with my Tsushima nagura. I do know that those come in hard and soft versions too but that’s about it; I’d probably prefer it to be an Aoto because then wouldn’t it be more valuable, haha. I guess the color could also be said to be no further from Aoto than from Tsushima; about midway between the two.

Also one axis I left out: smellovision. The Tsushima smells far stronger, and sniffing the Aoto and the unknown one I’d almost want to say the unknown smells more Aoto-like. Less strong than either of them though.

 

[Pie]

That’d be the cleanest looking aoto if it was one. Never really seen them that crisp. Also the lack of any visual irregularities turns me away from aoto.

As far as feel goes I’m with you, Tsushima tends to be soft, consistent and sort of gentle from what I’ve seen. My aoto is hard (but muddy??), fast and produces a scratch pattern.

But what do I know? I’ve only seen a couple of each.

Any chance you can pop out a test polish to show how it behaves?

 

[ReiHamono]

It’s a dehydrated and oxidized Tsushima, you have to take off the top layer and keep hydrating until it softens up.

 

[refcast]

My Tsushima yields slurry very slowly from the diamond plate but it does. Only super hard karasu were harder for me. I had gotten mine from iida tool.

I highly doubt it's a hard aoto, because those have some irregularity of shape or have patterning or inclusions

My Tsushima smelled like lacquer kind of

 

[GorillaGrunt]

It’s a dehydrated and oxidized Tsushima, you have to take off the top layer and keep hydrating until it softens up.

So how much should I sand off with diamond? Will it be visually apparent?

 

[GorillaGrunt]

I highly doubt it's a hard aoto, because those have some irregularity of shape or have patterning or inclusions

My thought too after looking at a bunch more

 

[ReiHamono]

Lap off a good amount and then soak in really warm water and retest, keep doing that until it’s to your liking.

You’re really going to love this stone once it softens up

So how much should I sand off with diamond? Will it be visually apparent?