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Thread: Thinning JCK Nashiji, what is happening here?

  1. #1

    Thinning JCK Nashiji, what is happening here?

    I had the first thinning session for a JCK Fu Rin Ka Zan W1 petty.
    Started with King1000 stone and after a while swithced to King6000.

    These are pics after ~5min of work with King1000:

    What is happening here? Why does it turn into blunt grey? Is it drawing material from the Nashiji finished Hira, which then sticks to the part between Shinogi and Hagane, or what?
    It originally looked like at JCK website; shiny metal colour with deep grinding scratches.

    Here are pics after ~15min with King6000:
    (I thought to move to safe side and continued with 6000 when I did not know what was happening...)

    Firstly, is my understanding correct here:
    1 = Hira, Nashiji finish
    2 = Shinogi line
    3 = Kireha, this part is stainless clad, or?
    4 = "Hagane line"
    5 = Hagane, White no1

    Secondly, what should I do here?

    - Take King1000 into action and give it a lot more work?
    Would this cause part 3 (Kireha?) to lose its cladding and end up in situation where everything below Shinogi is just White no1?
    How thick is the cladding in part 3?

    Resulting in somewhat thinner knife would not be a problem, actually I would prefer it.

  2. #2
    Senior Member
    Join Date
    Dec 2011
    Nothing bad is happening here, pretty much bevel comes not totally even, and you have not finished evening it out yet.. If you like a good looking knife, get king 1000 to work until you have even colour and no more rough grind marks left on the blade.

  3. #3
    Looks like the stainless cladding is as gummy as on the Hiromoto AS line. Many stones just leave a very dark finish on the cladding...

  4. #4
    Try going back to the 1k stone and work up some mud, and lighten up on the pressure. Repeat for the 6k. See if that improves the contrast.

  5. #5
    Scratch my last post, if you're trying to have the whole bevel shiny. I would try more pressure.

  6. #6
    Isn't this caused by the difference in hardness between the hagane and jigane and how they take to being abraded? I've seen a similar finish applied with a bocashi wire brush; the brush is hard enough to abrade the soft outer cladding (jigane) but not enough for the carbon steel core (hagane).

  7. #7
    Senior Member
    Join Date
    Jun 2012
    It's an uneven bevel finished on a grinding wheel, and there's nothing wrong. It took me hours to thin out my Fujiwara Teruyasu nashijii. I thinned out the nashijii portion as well until I got most of the spine to 2mm or thinner.

  8. #8
    Senior Member Benuser's Avatar
    Join Date
    May 2011
    Amstelveen, The Netherlands
    Quote Originally Posted by Rottman View Post
    Looks like the stainless cladding is as gummy as on the Hiromoto AS line. Many stones just leave a very dark finish on the cladding...
    It's not so much about the difference in hardness, it's more about the soft clad being much more abrasion resistant.

  9. #9
    Senior Member ThEoRy's Avatar
    Join Date
    Feb 2011
    Central Jersey
    For thinning I would use a lower grit stone like the gesshin 400 or beston 500. This way you get in, flatten the blade road, cut the cladding quickly and get out. Less time spent on the stone is less time wobbling around and making mistakes. Then move up to the next grit to achieve the scratch pattern you wish to have like the king 800 for example.
    Starting this harvest I'm a starving startling artist/
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  10. #10
    Senior Member labor of love's Avatar
    Join Date
    Dec 2011
    dirty south, louisiana
    thinning is the downside of stainless clad knives. i learned how to thin on a tojiro dp. i definitely made a mess of that knife.

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