Help me polish a honyaki

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ian

ian

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Hi all,

I've been working on polishing this Kippington 1095 honyaki. When I got it, the geometry was really quite nice for polishing, with only extremely minimal low spots in places that matter, and a lovely convex all over. So, I only really dropped down to a Chosera 800 for the initial work, going lower than that only on a couple spots on the back that won't matter so much for food release, while keeping them convex. Anyway, since the Chosera, I jumped up briefly to Gessh 2k and 6k just to lighten the scratch pattern a bit, and then spent a bunch of time on this uchimugori I got from @nutmeg. I think it's on the coarser side of uchimugoris, although it's the only one I've tried.

Technique-wise, what I'm doing on the uchi is laying the blade face on the stone with the edge toward me, putting my hands on the blade on either side of the stone with my fingers wrapped over the spine and my thumbs near the edge and directly over the stone, and going back and forth with wobble strokes over the full width of the convex geometry. I've tried with various amounts of water. A medium amount of water seems to work best, whatever that means.

It looks ok now, but not amazing. I'm not going for a true mirror polish (I don't know that that's really possible with this stone.) But I just want something that's even and looks good. Any suggestions on how to improve? Here are some vids I took trying to capture the scratches.





And here's the uchi.

uchi.jpg


I have some fingerstones too, also from @nutmeg, but they just seem to scratch the blade up when I use them and don't seem to improve the finish. They worked quite well on clad knives though. There's a low spot right underneath the maker's mark that I didn't want to fix, for fear of damaging the feather, so I'll have to figure out some way to get that to look more even too. Was hoping to use the fingerstones, but maybe something else will work.

Help!
 
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you should try to remove the vertical scratches but it‘s going to be very time consuming and you‘re going to need very coarse stones.
The color left from the uchigumori is good for honyaki.
6k may be too much, mirror gives dangerous scratchy results.
2-3k is somewhat cleaner on honyaki.
Your finger stones are too hard for honyaki. You need very, very, very soft ones. Very difficult to find. I doubt you can find some anywhere.
Hazuya/jizuya finger stones difference works for tamahagane but not for kitchen knives with very hard steel.
 
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nutmeg said:
you should try to remove the vertical scratches but it‘s going to be very time consuming and you‘re going to need very coarse stones.
The color left from the uchigumori is good for honyaki.
Click to expand...

I think the vertical scratches you see are from the uchi, actually. They're not that deep. Kipp's original sandpaper scratch pattern was horizontal. It's possible there are some vertical scratches left from the Chosera 800, but that's about it. Or maybe I'm confused. I don't think they're grind marks, though.
 
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There is a really thin line on the uchi that I can feel when I'm sharpening, though. It causes a very small hiccup when I go over it. It's not really thick enough to dig out or anything, but I did wonder if it could be hurting the finish. I think it's the sort of diagonal one in the middle of the stone.
 
ian said:
Hi all,

I've been working on polishing this Kippington 52100 honyaki. When I got it, the geometry was really quite nice for polishing, with only extremely minimal low spots in places that matter, and a lovely convex all over. So, I only really dropped down to a Chosera 800 for the initial work, going lower than that only on a couple spots on the back that won't matter so much for food release, while keeping them convex. Anyway, since the Chosera, I jumped up briefly to Gessh 2k and 6k just to lighten the scratch pattern a bit, and then spent a bunch of time on this uchimugori I got from @nutmeg. I think it's on the coarser side of uchimugoris, although it's the only one I've tried.

Technique-wise, what I'm doing on the uchi is laying the blade face on the stone with the edge toward me, putting my hands on the blade on either side of the stone with my fingers wrapped over the spine and my thumbs near the edge and directly over the stone, and going back and forth with wobble strokes over the full width of the convex geometry. I've tried with various amounts of water. A medium amount of water seems to work best, whatever that means.

It looks ok now, but not amazing. I'm not going for a true mirror polish (I don't know that that's really possible with this stone.) But I just want something that's even and looks good. Any suggestions on how to improve? Here are some vids I took trying to capture the scratches.





And here's the uchi.

View attachment 87353

I have some fingerstones too, also from @nutmeg, but they just seem to scratch the blade up when I use them and don't seem to improve the finish. They worked quite well on clad knives though. There's a low spot right underneath the maker's mark that I didn't want to fix, for fear of damaging the feather, so I'll have to figure out some way to get that to look more even too. Was hoping to use the fingerstones, but maybe something else will work.

Help!
Click to expand...


It has been my experience that using a progression of sand paper up to #2500, then moving to finger stones achieves the greatest results. In effect taking a blade up to near mirror polish allows you to see any remaining grind marks or scratches and thus be able to remove them. Once that is complete experimenting with a variety of finger stones allows you to achieve whatever finish you like, if you screw up, just repolish with the highest grit sandpaper and start over. I've done this with several high end knives and love the results. I've also found the knives are far less reactive this way, as the patina covers the entire surface. Stones IMO are good for wide bevels and or very flat blades with little convexity.

Just an opinion of course.
 
Hanmak17 said:
It has been my experience that using a progression of sand paper up to #2500, then moving to finger stones achieves the greatest results. In effect taking a blade up to near mirror polish allows you to see any remaining grind marks or scratches and thus be able to remove them. Once that is complete experimenting with a variety of finger stones allows you to achieve whatever finish you like, if you screw up, just repolish with the highest grit sandpaper and start over. I've done this with several high end knives and love the results. I've also found the knives are far less reactive this way, as the patina covers the entire surface. Stones IMO are good for wide bevels and or very flat blades with little convexity.

Just an opinion of course.
Click to expand...

Thanks for the thoughts! I might have done that, but I don’t really want a mirror polish on the hard steel, and no fingerstones that I have (or am likely to get) are soft enough to work below the hamon. See @nutmeg’s comment.

Maybe a good look would be to take the whole knife to a very high grit sandpaper polish, and then use fingerstones above the tempering line, but the core would have to really be mirror for the scratch pattern of the sandpaper not to clash with a fingerstone finish above the hamon. And a completely sandpaper finish removes all contrast so you can’t see the hamon. Also, after spending hours on a previous knife, I hate hand sanding. It’s much easier on my body to use a bench stone. Sword polishers (and fancy people like nutmeg) seem to use bench stones on convex geometry all the time, and in my experience it wasn’t very hard to get pretty uniform contact. It may well be that the convexity is making it harder for me to get a uniform finish, but on the other hand I’m not getting any faceting at all, which is the usual problem you see if you’re struggling with flat bench stones on a convex knife.

I assume you mean the knife is less reactive because the finish is higher on the blade? If so, I agree that that is the case. I’m not sure what you meant by “the patina covers the whole blade”, though.
 
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I can't confirm but suspect that they are using stones on the flat sections around the convex geometry, or simply using finger stones on whole blade. I don't see how you can create an even finish on a convex surface with using a flat surface. Either that or the stones need a concave surface reasonably symmetrical to the convex surface of the knife.
 
ian said:
I assume you mean the knife is less reactive because the finish is higher on the blade? If so, I agree that that is the case. I’m not sure what you meant by “the patina covers the whole blade”, though.
Click to expand...

When the grind marks and abrasions are removed from the surface of the knife (surface is more uniform), then refinished with hazy kasumi finish, the reactivity is significantly reduced in my experience. Did this with both of my Kato's and allowed a nice patina to reform. They are largely non reactive now to onions and tomatoes. If I leave juice on the blade it will obviously react but the smell and discoloration even after extended periods of prep work is essentially gone now.
 
Hanmak17 said:
When the grind marks and abrasions are removed from the surface of the knife (surface is more uniform), then refinished with hazy kasumi finish, the reactivity is significantly reduced in my experience. Did this with both of my Kato's and allowed a nice patina to reform. They are largely non reactive now to onions and tomatoes. If I leave juice on the blade it will obviously react but the smell and discoloration even after extended periods of prep work is essentially gone now.
Click to expand...

Yea, I just didn’t get the remark about patina. It’s definitely true that the higher grit your finish the less reactive your blade. Nooks and crannies in the surface give more total exposed metal, and it’s probably easier for microscopic amounts of juices and stuff to get trapped in them or something.
 
Hanmak17 said:
I can't confirm but suspect that they are using stones on the flat sections around the convex geometry, or simply using finger stones on whole blade. I don't see how you can create an even finish on a convex surface with using a flat surface. Either that or the stones need a concave surface reasonably symmetrical to the convex surface of the knife.
Click to expand...

No, they use them on the convex portions too. The finish on my knife in the OP is relatively even, it’s just scratchy, and the knife is convex all the way spine to edge while the finish is straight from bench stones. The point is you wobble the knife while you work, as described in the OP. Apparently some sword polishers even use convex stones when polishing, since if you’re wobbling it’s not important to have a flat surface, and convexity of the stone prevents faceting and keeps you from having to flatten too often. See this thread. There’s a vid halfway down.

https://www.kitchenknifeforums.com/threads/domed-whetstones.47295/
 
M1k3 said:
You could also try making an artificial "finger stone". Look through here for some possible ideas (I guarantee no actual results. Haven't done any of this, yet)? Polishing knife to emphasize banding
Click to expand...

Yea, it’s a good idea! I’ve tried that with the dremel pads on this knife, actually, with both uchi mud and King 800 mud. Didn’t do a whole lot, and even the pad was giving slightly visible scratches. Hmm. The King 800 mud in particular seemed to decrease the contrast, and made the finish look a bit worse. I should probably keep trying though.
 
I guess if you go 1000, 2000 and uchi strictly parallel to the length of the blade, the surface should be more even.
Using finger stones is possible but only when the finish is top after the uchi. It's like final make up.
Anyway, horizontal is the way to scratch ;)
 
ian said:
Huh, really? Interesting. I was scratching vertically since it seemed easier to wobble in the direction perpendicular to the convexity. Isn’t it easier to have faceting with heel to tip strokes?
Click to expand...
not sure you can get faceting on a honyaki, even at coarse
grit
 
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nutmeg said:
not sure you can get faceting on a honyaki, even at coarse
grit
Click to expand...

Hmm, I’m confused. The finish off the Chosera 800 looked faceted in places initially when I was working on it, but smoothed out with more and more wobble strokes. Obviously I have a lot to learn.

I’m also confused about the strokes along the length of the blade. When I do a wobble stroke vertically, the knife contacts something like a rectangular section of the blade. If I do a stroke heel to tip, it seems like each stroke will contact a very thin strip of the knife, so will be much less efficient. It’s like trying to polish a cylinder with a flat stone. If you go around the cylinder with the stone, you’ll make lots of contact. If you go along the length of the cylinder, you’ll contact in a single line. Seems less efficient?

I guess I was also trying to mimic what the sword polishers do, and they go perpendicular to the edge, at least in the couple vids I’ve seen. (Maybe I’m missing the finishing steps or my vids were misleading.)

maybe I should shut up about theory and go try it.
 
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Hi,

just a question in this context (as I have a similar project):

Has some of you tried a slurry, made with the Wa-Powder from JNS?
Have the powder (both grits #1000 #2000) here but could not find the courage to try it :D


Thanks.

Iggy
 
CE9E6D43-5A56-4153-9F24-62D7FA63A4B7.jpeg
Funny, there’s a very different quality to the lengthwise finish. Right now it looks super streaky, as expected, but I can see that it will probably be better in the long run. I’ve tried a number of different motions. Mostly, I’m now doing one hand on the tang, on hand sort of flat on the knife blade, fingers pointing toward the tip, exerting pressure in the desired places. At some point, I tried putting a 2x4 to one side of the stone, braced on the other side with some cast iron, so that I could keep the spine in contact with the wood and keep my scratches perfectly horizontal. Found this kind of annoying and not all that helpful. I also tried laying the knife down on a silicone mat (over a wet towel) on the counter and using the uchi like a giant fingerstone. This was working decently, although it’s more tiring and the scratches seem deeper, probably due to the increased weight.

Any thoughts on how to better stabilize my movements to get more perfectly horizontal scratches? I was also maybe thinking of reinstalling the handle so that half of the tang is exposed, just to give some extra weight and grip down there. Currently it’s hard to control from down there since it’s so far from the balance point of the blade.

I didn’t drop down to 1000 like nutmeg suggested, since it already had an uchi vertical finish, but probably I should have? Seemed weird to recreate the deeper scratches I’d erased. But maybe I should do it that way on the other side.

Iggy said:
Hi,

just a question in this context (as I have a similar project):

Has some of you tried a slurry, made with the Wa-Powder from JNS?
Have the powder (both grits #1000 #2000) here but could not find the courage to try it :D


Thanks.

Iggy
Click to expand...

Never tried their wa powder. But I’d imagine it would work somewhat similarly to using stone powder from your own stones, without all the effort to get it? Dunno though, maybe theirs is special. I haven
 
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