Aoto perpendicular layers

Discussion in 'Sharpening Station' started by musicman980, May 21, 2019.

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  1. May 21, 2019 #1

    musicman980

    musicman980

    musicman980

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    I don't see much info on why aoto are usually cut perpendicular to the layers instead of with the layers. Is there some science to the cutting action, or was it just the easiest way to cut them out of the mine?
     
  2. May 22, 2019 #2

    childermass

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    I once was curious about that too and asked Shinichi Watanabe about it. This was his reply:
    'Yes, natural stone has the usable side like wood.
    We call Itame, cross grain and Masame, straight grain. Because natural stone piled and grew.
    You don't have to think about Aoto so much. Some people like Masame. However some people like Itama. I think Itame has stronger shaping power.'

    I also once read that there are lots of Aoto stones that actually don’t have real layers and can be used on all sides.

    Why they chose to cut the rocks in a certain manner, apart from being a bit faster maybe, I cannot say though.
     
  3. May 22, 2019 #3

    musicman980

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    Cool info from Watanabe. It would be interesting to see if anyone has an obliquely cut jnat that's not an aoto.
     
  4. May 22, 2019 #4

    refcast

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    I have some thai stones that are flattened on all four sides. . . each side sharpens a bit differently. The parallel grain sides release grit a bit faster and feel just a bit coarser, and the perpendicular feels a bit more resistant and finer. They're about the same hardness, and the stone isn't completely consistent throughout. I don't think it matters too much, though maybe tradition has it a certain way so they don't break, or waste stones.
     
  5. May 22, 2019 #5

    musicman980

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    Interesting - have you also tried its "end grain" ?

    Something else to think about. With grain, cross grain, and end grain might act differently for wood than for stone, in that trees grow with the grain, and layered stone "grows" across the grain.
    It can't make that much of a difference though, since stone particles don't interlock like wood fibers do.
     
  6. May 23, 2019 #6

    refcast

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    Oh, so I should be more specific then. So the stone is a rectangular prism with sediment deposited planar. And what I posted was in reference to the four long sides. So two of them are slower, finer (edge grain) and the other other two are coarser, faster (on the plane). And then the edge are just a tad finer feeling, but I really don't think it matter much. There was more difference with an actual soft patch of the stone than the stone orientation. It's pretty uniform in each direction.
     
  7. May 23, 2019 #7

    musicman980

    musicman980

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    Gotcha, thanks.
     
  8. May 23, 2019 #8

    childermass

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    The only stone I know about that has different sharpening properties depending on the used side is Phyllite:
    IMG_3234.jpg

    This is the type of stone that is found near Wästikivi in Finland. These are nice stones and a great medium grit option for carbon steel. Too bad they don’t cut it in cubes so you can really use all three orientations.
     
  9. May 24, 2019 #9

    Walla

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    There is this place that does...

    https://www.wastikivi.fi/Whetstone

    Take care

    Jeff
     
  10. May 24, 2019 #10

    childermass

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    Awesome, thanks for sharing!
    Last time I visited the site that option was not available.
     
  11. May 25, 2019 #11

    ian

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    Not sure there’s such a thing as end grain in stone. Wood has (1-dimensional) fibers, so there can be two kinds of sides, edge grain and end grain. Stone has (2-dimensional) layers, so there’s only cross grain and straight grain. (And I guess you could do oblique cuts in both, if you want to make it more complicated...) But maybe you and refcast already ironed this out and I’m just contributing noise. Cheers.
     
  12. May 25, 2019 #12

    musicman980

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    Never thought about that before, the dimensionality. Thanks! As for that wastikivi stuff, I'm thinking it would be ideal for camping or just roughing it in the woods. I'm all for simplicity, but that's just not enough stone for a guy like me. My knives sprawl out on my nakayama.
     
  13. May 25, 2019 #13

    refcast

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    upload_2019-5-24_23-11-21.png

    This picture assumes that the stone is cut a particular way. I assume some stones aren't perfectly like this or are even slanted off to one side. But there is no clear end/edge grain distinction like in wood. Because in wood the main unit is the cylindrical fiber bundle, whereas in most stones its a plane of sediment. Though the material can vary along the plane, and the composition varies or is completely different along the planes oftentimes. We do get things like renge and karasu and so on.
     

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