I was asked how Kitaeji reacts to natural Aoto.
I did not try only Aoto but I tried also other natural stones which I have in my collection. I do not have so many natural stones other than the finisher from Kyoto mines so I could try only 7 stones.
Aoto:
This is my favorite Aoto. The mine is unknown but it feels like a rare and very good Akamonzen Aoto.
It has small red brown dots at the surface.
The Aoto is a middle stone. Though this Aoto is on the fine side of Aoto you can still see some scratches. It does not destroy the Kitaeji pattern so it will be a very good middle stone or pre-finisher.
Now some finish stones which make semi mirror or mirror finish.
These are Mikawa Nagura (Mejiro), Tsushima Nagura (from mountain) and Translucent Arkansas.
Mikawa Nagura Mejiro
Big Tsushima Nagura (from mountain)
Translucent Arkansas
Now the results (they look almost same):
Mikawa Nagura Mejiro Polish
Tsushima Nagura (from mountain) Polish
Translucent Arkansas Polish
You can see that these finishing stones are not suited for Kitaeji polish.
Now back to some natural middle stones Iyo and Amakusa:
Iyo Stone (on hard side and porous)
Iyo Stone Polish
This Iyo stone was very very slow. But the result was not so bad as a middle stone.
But still not good enough compared to the 3 fingerstones I selected.
Amakusa Stone
Amakusa Stone Polish
Amakusa was very slow too. Polish was similar to Iyo.
Last is my favorite middle stone Aizu:
Aizu Stone
Aizu Stone Polish
Aizu was the fastest of all stones tested here. You can see scratches but you can see the Kitaeji patterns too. Aizu is a very good middle stone but I can not find any Aizu now.
After every test and end of all the tests I used Hakka or Maruka fingerstone to get the Kitaeji pattern back.
Here the Shigefusa Kitaeji knife after all the tests:
Maruka Fingerstone Polish
Hakka Fingerstone Finish
Conclusion:
Middle stones of Aoto, Amakusa, Iyo and Aizu does not destroy the Kitaeji patterns. They can be used if you do not care about scratch patterns.
But these middle stones are a bit brittle so I think you must enforce them with Japanese paper and Cashew lacquer if you want to use them as fingerstones.
And the finish is more bright and not so good as the finish with fingerstones I have selected.
Finishing stones which make semi mirror or mirror finsih destroy the Kitaeji patterns. Mikawa Nagura, Tsushima Nagura and Translucent Arkansas are those stones.
If you want a nice Kasumi finish the results of this test is useful too.
Edit to add on 27th. July:
My friend Maxim at
JNS has also blog about fingerstones: