Polishing knives

Discussion in 'Sharpening Station' started by T85, Jan 13, 2020.

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  1. Jan 13, 2020 #1

    T85

    T85

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    hello my fellow knives enthusiast! I have a couple of honyaki sujihiki and yanagiba that I want to mirror polish. I have no idea of to do it. Can some body here tell me how to do it? What would I need? Any answers or links would be helpful, thanks guys.
     
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  2. Jan 13, 2020 #2

    gman

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    a rabbit hole opens up in front of you. jump into it? [Y/N]
     
  3. Jan 13, 2020 #3

    T85

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    Lol this would be my first knife rabbit hole! So Yes head first
     
  4. Jan 13, 2020 #4

    M1k3

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    I've done mirror polishing before. It was very satisfying. That said, I'd only do it again if I was paid a decent amount to do it.
     
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  5. Jan 13, 2020 #5

    TRPV4

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    What sort of finish are you starting from?
     
  6. Jan 13, 2020 #6

    Garner Harrison

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    If no one minds I could also do with some help with polishing, just got my Mazaki knife and I want to know more about how to polish it properly. Without scratching the Hira/Tsura and messing up the Shinogi line.
     
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  7. Jan 13, 2020 #7

    TRPV4

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    You got into this quite quick didn't you!
     
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  8. Jan 13, 2020 #8

    Garner Harrison

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    Into knives? Or into looking around into how to polish my knife :D
     
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  9. Jan 13, 2020 #9

    TRPV4

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    Both lol (sorry for hijacking thread)
     
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  10. Jan 13, 2020 #10

    T85

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    I want to start with my 1095 honyaki sujihiki. It’s has a nice patina right now, so I guess the first step would be to remove the patina, but I don’t know what the best way to do it as I’m also new to this
     
  11. Jan 13, 2020 #11

    T85

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    Jump right in bro! This rabbit hole is wide
     
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  12. Jan 13, 2020 #12

    ian

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    The patina will come off no matter what if you’re going to start polishing. If you want to take it off without changing the existing finish much, use flitz or simichrome or another metal polish. But don’t bother if you’re then going to polish it.

    I’ve only ever tried to mirror polish something with sandpaper, which works, but is a huge pain. You just start at a low grit and go higher and higher till you can’t see scratches. It helps if you alternate the direction of movement when you switch grits so you can verify that you have removed the previous scratches. I was only doing a 135 mm petty... I wish you luck on your yanagiba....

    Probably most will say that to preserve the crisp shinogi on your yanagiba you should at least use sandpaper attached to a hard, flat backing, or preferably use stones instead. I’ll let them tell you that, though. I have no real experience here.
     
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  13. Jan 13, 2020 #13

    Dendrobatez

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    If you're looking to go the sandpaper route for this then Nick Wheeler videos are a good place to start for hand sanding technique.
    I agree with @M1k3 though, in that it's a long process and would have to be something special for me to take it to a mirror.
     
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  14. Jan 13, 2020 #14

    gman

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    i'm don't have a ton of experience, but the couple of knives i've polished so far i did entirely on stones, and using that method, the first thing you will discover is whether the grind has high and low spots. probably start with a medium grit and you will find out pretty quickly if there are spots where a flat stone just can't reach. from there decide whether you want to go to the effort of dropping down to a course grit stone to flatten the bevel, or if you want to switch to sandpaper. i believe you can keep a crisper shinogi if you stick with nice flat stones, but it will be a lot more work.
     
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  15. Jan 14, 2020 at 5:49 AM #15

    Garner Harrison

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    Sorry if it seems like I'm trying to hijack the thread but I really want some advice on polishing my new knife and I think the advice I get could also help out T85. :D

    Ive attached some pictures of the knife for reference. The blade is sharpened via the hamaguri technique from the store and I know how to maintain that thanks to Jon's videos, but the source of my trouble is the tip section and the "fake" shinogi line. The shinogi line is like others have said in other threads, there and is not there at the same time as it is rounded. Ive talked to others about this and so far I'm towards removing the near mirror polish on the hira if it seems like I cant maintain it since I plan on getting finger stones later.

    The finish I'm going for is a kasumi finish, so I want to mainly focus on that and Im wondering if I just do hamaguri sharpening would it be likely I start to mess with the unique shinogi line. Another question would be if I do sharpening it would I eventually end up with a harder shinogi line if I do not round it while sharpening? I wont try and make this happen as I dont plan on removing that much material just for aesthetic. Finally is there any videos, tips and other threads I have missed that would help me with polishing/sharpening the tip section of this knife? Specifically this style bevel towards the tip, as I'm a very unsure about it (e.g. where to apply pressure and how to hamaguri sharpen it).

    Thanks in advance to whoever responds! And I hope T85 also gets some nice help out of this :D
     

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  16. Jan 14, 2020 at 6:19 AM #16

    T85

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    Thanks. I highest grit stone that I have now is 6000. Do I need a higher grit? Perhaps buying super high grit sand paper is cheapest way, but I do want to nice shinogi to stick out
     
  17. Jan 14, 2020 at 6:21 AM #17

    M1k3

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    Use a stiff backing on the sandpaper. Cork, piece of wood, rubber block, etc.
     
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  18. Jan 14, 2020 at 6:22 AM #18

    T85

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    I’m definitely going to watch those videos tomorrow!
     
  19. Jan 14, 2020 at 6:24 AM #19

    T85

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    So How many hours (average) would it take to take 270mm to a mirror polish?
     
  20. Jan 14, 2020 at 7:19 AM #20

    Alder26

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    It takes longer as the grits get higher. But as an example it took me 2 hours to do a 1000 grit polish on one side of my watanabe
     
  21. Jan 14, 2020 at 4:28 PM #21

    Dendrobatez

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    4 hours for a 240mm k tip like this, key is to make sure you get all of those lower grit scratches out - a lot of times you wont see them again until you hit 2k grit. If it's pretty reactive like this mazaki itll get a fairly smooth patina real quick.

    IMG_20180410_122849.jpg

    IMG_20180429_192717.jpg
     
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  22. Jan 14, 2020 at 9:06 PM #22

    nutmeg

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    Mirror on honyaki is hardcore.
    The problem is the surface. One may believe the core on his clad knife is mega clean but put on a larger surface like a honyaki, every single scratch will appear at many angles of view. You may have seen pictures here and there on Instagram and you thought it's clean but in reality it's scratchy.
    (I'm not saying all the mirror on any honyaki you've seen look lazy and ugly in real but more than you think)
    And a clean mirror to maintain is challenging if you want to use the knife.

    I don't know what grit/stone I would use. Generally above 3k the surface began to look scratchy so I finished cleanly on soft Uchigumori.
    I tried high grit synth, some other very fine Jnats.. never got a clean surface.
    Also, using stones means that the geometry is perfect, without any low spots and this doesn't exist, even on very expensive knives.

    If I had to do the job, I would do it only with buffer wheel and try to keep in mind that scratches- even large are not such a big problem.
     
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  23. Jan 14, 2020 at 9:15 PM #23

    nutmeg

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    The time depends on your strategy and on how flexible your mind is with cleanness and mirror intensity.
    Admitting you have a full time job, you need sleep, eat etc.. and you don't have any buffer wheel or machine:
    it's now 10:15 pm..
     
    Last edited: Jan 14, 2020 at 9:21 PM
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  24. Jan 14, 2020 at 9:17 PM #24

    nutmeg

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    ..you can't finish this week :p
     
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  25. Jan 14, 2020 at 9:27 PM #25

    gman

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    a conservative estimate would be 2 hours per side, per grit. i have a 10 stone progression from extra extra course diamond to 12k synthetic, so that's 40 hours total, but i spread that over a few weeks. i'm sure there are faster ways to do it, but i enjoy the meditative process as much as the final result.

    if you want to do the choil and spine too that would be all wet/dry sandpaper work, and best to do it first to avoid accidentally scratching the blade later.
     
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  26. Jan 15, 2020 at 3:17 AM #26

    pentryumf

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    *chime*
    I would echo Nutmeg, it took me close to 32 hrs to take a2 270 gyuto to near mirror, using 400 to 20000. A close to mirror is more than doable if you can put in the time.......a long time.
    Optical fibre polishing pads to 0.1 micron will produce mirror, and would be absurd. Near mirror, sandpaper and patience, the last of my shinogi came out with okudo suita finger stones. It was a blast but I won't do it again.
     
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  27. Jan 15, 2020 at 3:47 AM #27

    ian

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    Y’all indulge in a peculiar brand of masochism. My arm joints all hurt reading this thread.
     
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  28. Jan 15, 2020 at 3:39 PM #28

    harlock0083

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    I've polished a few knives, after 20+ hours in I stop and think about all the bad choices I've made and then I go cry in basement.
     
  29. Jan 15, 2020 at 7:59 PM #29

    SilverSwarfer

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    Here’s a Shi.han I sanded to “near mirror.” I put about 6hrs into this, using 800-1k-1.5k-3k sandpapers of various types. I wrapped some durable disposable foodservice towels around a 1” square wooden block about 3.5” long. I found that using some Autosol and adding some 3k SIC powder made the work go faster. As I progressed grits I went perpendicular to the last, always “pulling” with pressure (sanding pressure 1 direction only). Work was spread over about 3 weeks.

    Pics aren’t great. Apologies. There is a pic showing original finish.
     

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  30. Jan 15, 2020 at 8:18 PM #30

    da_mich*

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    Honyaki? Sujihiki? Yanagiba? Mirror polish? :haironfire::haironfire::haironfire: That sounds very crazy. I know how to mirror polish a blade very fast and easy but i don´t tell you how to rape your Honyaki knife :haironfire::haironfire::haironfire:. I will not go to jail for aid to rape.
     
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