Jnat experts wanted: what do I have?

[Zwilling]

I bought this hone about 15 years ago from a woodworking store. It was sold to me as a very fine finishing stone. The box has no markings other than “Karasu 10”. I know that Karasu means crow in Japanese and refers to the pattern, not the type of stone as far as I know.

Does anyone know what it might be?

As far as the stone is concerned, it is very hard, and it takes a long time to raise a slurry with Nagura. Some razors seem to respond well to being finished on it, but others less so. Even after all these years, i am still figuring this stone out. Perhaps I need the right tomo nagura for it?

[Steve56]

Can you post a good image of the ‘skin’ on the bottom edge in the first image?

[Toroblanco]

On those hard stones a 1200 Atoma or equivalent DMT to creat a slurry is a great way to start after you set the bevel. Then finish with your tomo.
Great looking stone by the way!

[Zwilling]

Here is the skin, only visible on one side:

[Gasman]

The skin is not on the bottom of the stone? Nly the sides?

[Bill31521]

No expert here. Anyway looks like both sides may be usable. Carpenter shop may indicate it is a tool stone but no way to find out till you find out. This is how i test stones, not the only way or best way its just what i do. Take a razor and do a slew of half strokes on it. Then i take wipe it with a white paper towel and see if it self slurries. The stone color is what you would see. Then I would take a razor and look at the scratch patterns to see how course they appear, water only, then with slight slurry from a diamond plate. Some karasu are scratchy. Finish a razor to 12k or so with a synthetic stone and then see what that stone does to that edge in a shave test. I would use a diamond plate generated slurry about the size of a quarter and see. Do that and test shave it.

[Zwilling]

That’s right! The two sides are pictured in my first post.

[Sandr]

Does anyone know what it might be?

Yes, this is Takashima. Characteristic color and cut.