Razor stone hardness, quality, abrasive speed and more.....
This was from the ''Kiita fan club'' thread. Better to start a new
thread on this matter:
Quote:
Originally Posted by
alx
Sharpman
I like Okudo stones, the good ones are very good and razor users seem to cherish them. But remember that each mine gave up all qualities of stone, some good, great and just average. So seeking out the really great stone is the challange. Great stone has a larger quantity per pound of grit as weighed against binder. More grit means faster cutting action.
For razors the size of the grit is important and although all the mines provided a certain amount of razor quality stone at one time or another, by far the greatest portion of razor (kamisori toishi) hone stone came from the few mines clustered around the Nakayama mine in the Umegahata valley. The reason for this is logical and scientifically proven, the finest of the wind blown (aeolian) material settled in this part of the Tamba Terrane during the original volcanic event that belched forth the materials that make up the sharpening stones as we know them. Logically the "closer to the source" and coarser material settled first in the area of the terrane that now is on the map as apparing farther to the west near Kameoka City or beyond, while the finest particles traveled farther while suspended in the easterly blown wind and settled closer and near to what is now thought of as Kyoto. Of course as you may know, the Original Event took place during the late Permian or Jurassic Periods while the infant hitch hiking Tamba Terrane form resided on the Pacific tetonic plate in the area of the globe now known as Hawaii. Evidently it took over 2,000,000 years to transport piggyback style to Japan as the Pacific Plate moved west while diving under the various Asian Plates.
So yes, Okudo are worth more than usual if you are comparring against the more remote mines to the west, and yes, some Okudo, if they are made up of super fine grit, are worth more than ususal when comparred to similarly priced but inferior stones.
Sorry for the long answer, which is about 1/3 of my first version, but it appears I have too much time on my hands. Alx
Thanks Alex, great answer!
Some more question if you don't mind. I don't get the chance to ask
an expert like yourself questions on tennen toishi everyday. What is the
ideal finishing stone for razors?
My guess:
- a rather hard to very hard stone,
- works quickly(high abrasive power)
- sheds superfine grit
- free of impurities
Could the ideal razor finishing hone also be ideal for plane blades? I sharpen
plane blades a lot and usually finish on the 8000 synthetic stone, but now also
use the chinese guangxi hone, which is finer. Razor guys go up to 30.000
Which strata produces the hardest and/or finest stones? I have
been following this forum for a few years now and it seems that people
here like asagi stone the most because they are the hardest and finest. Asagi
is from the tomae strata. I find this confusing as the suita strata is even deeper.
Shouldn't the deepest strata produce the hardest stones because all the weight
from above has/is compressed it?
A lot of people are using very hard stones with fine nagura slurry. I am
guessing they do this because otherwise the stone is too slow and the
sharpening process would take too long. I think another reason might be,
is that a super hard stone sheds its own abrasive super slowly which also
makes it possible for the nagura slurry to break down to superfine particles.
Which type of stone is/was preferred in Japan now and in the past, an extre-
mely hard stone, that almost doesn't release its grit and should be used with
nagura slurry, or a slightly less hard stone that releases very/super fine grit
without nagura slurry?
What makes certain finishing stones work very quickly while others are much slower?
Simple answer I could think about would be the abrasive concentration in the stone.
Where do the whetstone shops in Japan buy their stones? The only mountain still being
mined is maruoyama AFAIK, so where do the shops get their nakayama, ozuku, shoubudani
... stones from?
Thanks Alex in advance for answering.
Sharpman