This is an Oozuku Karasu.
It's a big one, 200x75x25, and as you can see, it's got all kind of Karasu spotting. I got it for Kamisori, because they do tend to like longer stones.
Anyway, I was trying it out for the first time tonight, and I noticed something interesting...
Here is a fresh Koma slurry. My koma is pure white, so the gray comes from the stone.
Here is the same slurry after some honing.
It's getting thicker, so I made fresh slurry, and added water, and then honed some more.
And this happened:
That is clearly NOT gray.
Clearly, there is something in this stone that causes oxidation in the steel, turning the slurry rust colored.
I've heard of this before, but not seen it. It could be what the Japanese honers I know call "Gunpowder" (煙硝), meaning a high sulfur content (I think...). What effect does this have on the honing? I have no idea. But it sure is interesting.
4 comments:
What a beautiful stone!
Very nice stone, Jim.
By the way, I have tried 4 japanese stones until now (the one I'm waitng from you will be the fifth), and it almost ALWAYS happens to me that the metal particles in the slurry oxidize like that, turning the slurry orange.
Sometimes it happens even with my coticules (i had posted something here: http://www.coticule.be/the-cafeteria/message/4074.html).
I think it has to do with the steel too, and maybe the water you use...
Certainly if it never happened before to you, it must be the stone.
Very interesting though.
This shouldn't cause problems with the honing, but I have noticed that when the slurry turns orange like that, the blade gets stained. And this is really a pain because to clean the stains you risk ruining the edge.
Thanks Nikolay.
G,
Interesting! It must be something in your water, I think...This is definitely the first time for me, after more than a dozen Japanese stones.
Now the big question, how much
did this stone cost?
Beautiful stone. Congratz
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