Help me polish a honyaki

[ian]

Hmm, how does one get the lengthwise finish to be less streaky? More mud, less pressure, changing the line of contact on each stroke so that your polishing starts on one stroke near the spine, then the next stroke a little more toward the edge, then more and more, and then starting back toward the spine when you reach the edge?

Having more trouble getting the streaks out with lengthwise strokes than widthwise.

 

[lemeneid]

Hmm, how does one get the lengthwise finish to be less streaky? More mud, less pressure, changing the line of contact on each stroke so that your polishing starts on one stroke near the spine, then the next stroke a little more toward the edge, then more and more, and then starting back toward the spine when you reach the edge?

Having more trouble getting the streaks out with lengthwise strokes than widthwise.

I’m no pro, but this is how I do it. You can lay the stone perpendicular or parallel depending on how you need to get the scratch pattern laid out. Also one side of my stone is convexed while the other is totally flat, which makes it more versatile depending on the grind of your blade.

Beware though, it’s not for the faint of heart, you will lose a lot of metal and stone doing this as you constantly have to flatten and I use quite a bit of pressure so it is very aggressive. But definitely faster than sandpaper.

Also helps if you have a vice to keep the knife in place, doing this free handed can be tiring and you’re prone to errors. And at higher grit, about 1500 and above, I find it might be good to start having a sanding block and diamond compound, it can speed up the mirroring process quite a fair bit.

 

[ian]

Ah, so you are holding the stone on top. Interesting. I tried that briefly a few days ago, but reverted to knife on top. It did seem potentially easier to get a straight scratch pattern with the stone on top.

 

[lemeneid]

Ah, so you are holding the stone on top. Interesting. I tried that briefly a few days ago, but reverted to knife on top. It did seem potentially easier to get a straight scratch pattern with the stone on top.

Yup, but its a total stone destroyer, only do that if you don't mind wrecking it and changing your stone, you can see from the last picture I posted, how convex the stone got after. But it is EXTREMELY fast in shaping your blade and putting very straight scratch pattern.

Would love to know how the pros do it. Think most do with knife on top?

This is mine after 1000 grit sandpaper. Only did the heel half where you can see it’s almost mirror, but the tip half can use a little more work and my kanji is almost disappearing now

 

[ian]

Yup, but its a total stone destroyer, only do that if you don't mind wrecking it and changing your stone, you can see from the last picture I posted, how convex the stone got after. But it is EXTREMELY fast in shaping your blade and putting very straight scratch pattern.

Would love to know how the pros do it. Think most do with knife on top?

This is mine after 1000 grit sandpaper. Only did the heel half where you can see it’s almost mirror, but the tip half can use a little more work and my kanji is almost disappearing now

View attachment 87699

Hmm, I haven’t noticed massive dishing. Lots of mud, though. Confusing. Maybe I’m just using the stone surface more evenly than when I sharpen, so it’s less dishing and more just wearing away evenly. I’m probably not using as much pressure as you are either.

With the stone on top, I find the scratches are generally a bit deeper, perhaps because the weight of the stone translates to a lot of extra pressure.

I ended up just doing more knife on top strokes with a lot of mud to try to get it as even as possible. Then I happened to find this “fingerstone” (or would you call it a hand stone, given its size?) in my cabinet that I never use. I have no idea what it is, but it happens to work well on the hard steel! It doesn’t scratch up the finish like the others I was trying, and is making it more even. Looking forward to trying as well with some other soft fingerstones that are arriving tomorrow. I’m not really going for mirror, so I’ll probably just keep going with fingerstones for a bit and then call it done.

 

[Luftmensch]

You can work with scratches!

When I thin my daily drivers, I feel compelled to go through the process of refinishing the blades. I do a brushed finish on the flat of the blade, and a haze on the bevel. Getting a good satin brushed finish can almost be as maddening as any other type of polish. It depends what standard you hold yourself to!

Before getting to the brushed finish, you can polish the surface to the final grit level you want, or even one git higher. At that point I have found good success doing more or less what @lemeneid said. Knife below and abrasives above. Put the aesthetic scratches on the blade by doing very controlled passes across the surface. I even use ruler to ensure I am keeping the passes straight. The lighting in this photo is super harsh and revealing:

This is the front quarter of a 210mm gyuto. The brushed finish is as straight as I could manage! Drove me mad... had to do many resets. On average I would consider this finish to be 70% perfect. Suits me fine. Again, it is a knife that is to be used. It is a dirty 5000 on the core steel, a painfully done 600 grit brush on the face and a dirty fingerstone finish on the bevel. It looks quite different in normal lighting. The brushed finish is quite bright and shiny, the bevel is a nice dull kasumi and the bevel is mirrorish. There are some nice contrasts.

On uchigumori (bench and finger stones)... Sword polishers have a collection that they can match to the steel they are working with. As @nutmeg pointed out, yours is likely too hard. It is easy to get hung up on tradition. Anything that gets the job done is fine by me! You don't have to use uchigumori . As you noted in your previous post, you may find stones better matched to your knife. I have a Shobudani stone that reliably leaves a lovely scratchless kasumi finish. It may be too cloudy for hamon though. Experiment with what you have in your tool kit!

 

[lemeneid]

You can work with scratches!

When I thin my daily drivers, I feel compelled to go through the process of refinishing the blades. I do a brushed finish on the flat of the blade, and a haze on the bevel. Getting a good satin brushed finish can almost be as maddening as any other type of polish. It depends what standard you hold yourself to!

Before getting to the brushed finish, you can polish the surface to the final grit level you want, or even one git higher. At that point I have found good success doing more or less what @lemeneid said. Knife below and abrasives above. Put the aesthetic scratches on the blade by doing very controlled passes across the surface. I even use ruler to ensure I am keeping the passes straight. The lighting in this photo is super harsh and revealing:

View attachment 87703

This is the front quarter of a 210mm gyuto. The brushed finish is as straight as I could manage! Drove me mad... had to do many resets. On average I would consider this finish to be 70% perfect. Suits me fine. Again, it is a knife that is to be used. It is a dirty 5000 on the core steel, a painfully done 600 grit brush on the face and a dirty fingerstone finish on the bevel. It looks quite different in normal lighting. The brushed finish is quite bright and shiny, the bevel is a nice dull kasumi and the bevel is mirrorish. There are some nice contrasts.

On uchigumori (bench and finger stones)... Sword polishers have a collection that they can match to the steel they are working with. As @nutmeg pointed out, yours is likely too hard. It is easy to get hung up on tradition. Anything that gets the job done is fine by me! You don't have to use uchigumori . As you noted in your previous post, you may find stones better matched to your knife. I have a Shobudani stone that reliably leaves a lovely scratchless kasumi finish. It may be too cloudy for hamon though. Experiment with what you have in your tool kit!

That looks amazing!

I think to make it even more perfect to your high standards you would have to use some guided system to keepthe scratches as straight as possible and pressure as consistent. And before that the blade face would have to be as flat as possible so you wouldn't get any low or high spots which would make the scratch pattern too deep or shallow.

I'm really curious though, how did you manage to keep the scratch pattern on the bevel so consistent and almost parallel to the edge.

 

[ian]

You can work with scratches!

When I thin my daily drivers, I feel compelled to go through the process of refinishing the blades. I do a brushed finish on the flat of the blade, and a haze on the bevel. Getting a good satin brushed finish can almost be as maddening as any other type of polish. It depends what standard you hold yourself to!

Before getting to the brushed finish, you can polish the surface to the final grit level you want, or even one git higher. At that point I have found good success doing more or less what @lemeneid said. Knife below and abrasives above. Put the aesthetic scratches on the blade by doing very controlled passes across the surface. I even use ruler to ensure I am keeping the passes straight. The lighting in this photo is super harsh and revealing:

View attachment 87703

This is the front quarter of a 210mm gyuto. The brushed finish is as straight as I could manage! Drove me mad... had to do many resets. On average I would consider this finish to be 70% perfect. Suits me fine. Again, it is a knife that is to be used. It is a dirty 5000 on the core steel, a painfully done 600 grit brush on the face and a dirty fingerstone finish on the bevel. It looks quite different in normal lighting. The brushed finish is quite bright and shiny, the bevel is a nice dull kasumi and the bevel is mirrorish. There are some nice contrasts.

On uchigumori (bench and finger stones)... Sword polishers have a collection that they can match to the steel they are working with. As @nutmeg pointed out, yours is likely too hard. It is easy to get hung up on tradition. Anything that gets the job done is fine by me! You don't have to use uchigumori . As you noted in your previous post, you may find stones better matched to your knife. I have a Shobudani stone that reliably leaves a lovely scratchless kasumi finish. It may be too cloudy for hamon though. Experiment with what you have in your tool kit!

Hey, that is a cool finish. Got any pictures in other light?

You do have to use an uchimugori if it’s your only polishing stone and you don’t want to get another.

But the fingerstone is making things much better. Here’s the current state of the art, but more work needs to be done.

 

[Luftmensch]

That looks amazing!

Thank you kind sir! ☺

I think to make it even more perfect to your high standards you would have to use some guided system to keepthe scratches as straight as possible and pressure as consistent. And before that the blade face would have to be as flat as possible so you wouldn't get any low or high spots which would make the scratch pattern too deep or shallow.

I'm really curious though, how did you manage to keep the scratch pattern on the bevel so consistent and almost parallel to the edge.

Kind of strange... For some reason I got hung up on getting the scratches nice and uniform but decided to neglect the kasumi (not a perfect haze) and bevel (scratchy mirror). I guess thats why I would down grade the overall finish? Ultimately those lower areas get scratched so I figured the extra effort would be wasted.

Like you observed, start with a flat surface. My 'cheat' was to use a ruler. I have a little block of wood. Maybe about 20-30mm wide and 10mm long. I would wrap the sandpaper around that and guide it with the ruler. You're spot on! Changes to pressure or veering off the guide would change the scratches. The entry and exit points were also big causes of wobble!

I got pretty even scratches on the kasumi by guiding the finger stone with two or three layers of vinyl tape. That tape is quite nice to use as it is thick but can be stretched into nice sweeping curves.

 

[Luftmensch]

Hey, that is a cool finish. Got any pictures in other light?

Not yet! It is the dead of the night here... I couldn't get angles with artificial illumination that looked natural. I'll see if I can remember tomorrow

You do have to use an uchimugori if it’s your only polishing stone and you don’t want to get another.

Hehehe... maybe? You could revisit the mud idea? I havent used a dremel pad. I've used the furry side of tanned leather - it seems to be forgiving and scratch free.

But the fingerstone is making things much better. Here’s the current state of the art, but more work needs to be done.

Looking great! Keep at it. I am loving the adventure.

 

[inferno]

I dont have any honyakis!

But having "polished" about 15 or so bevels and then a few whole knives including 2 of my own single bevel mono santokus i have some input on polishing.

i feel for clad blades you get good contrast from 800 or so. the shapton pro1k, naniwa pro 800, king 1k hyper, all good (but the hyper creates silver scratches).

moving up i feel the naniwa pro 2k is good for contrast. the shappro is quite good but much harder to get the wanted result.

then i feel clean cut kit 4k is good. also glass gray 6k will work. but you have to work the slurry.

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also tried an uchigumori and 2 different coticules. the difference in end result with uchi vs 800-2k-4k is minimal, but with the synths you have to kinda know how to do it to get the wanted result. with the uchi you just put the blade on there and polish away. there can only be 1 result. and its the same result every time. i would say my uchi creates a hazy finish comparable to maybe 2-4k somewhere. probably around 3k in shapton numbers.

the coticules (i have newer mined ones) they create this hazy finish, its much finer than the uchi, but still hazy. not a mirror. maybe twice as "fine". these are also very easy to use since there can pretty much only be one end result. and you get an even finish just like with the uchi.

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i have also "mirror polished" a few knives, with stones. and if you dont have like 5-10-20 extra hours to spend maybe this is not for you.
anyway i flattened and polished 2 single bevel santokus. carbon steel at maybe 62-63hrc or so. and with stones you really have to erase all previous scratches before you move up in grit. otherwise those will shine through.

even after the shappro 12k and SS12k they are not really really mirror imo. from some angles they are but from other angles you can see all the scratches.

i dont know what stone would be needed to create a true mirror finish but it must be in the 15-30k range imo. and it would probably take forever.

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if one wants a good mirror polish i think different sandpapers from C to F, maybe up to 2-3k would be the fastest, and then finish it off with green Cr-oxide or 0,5 micron diamond on wood/felt/leather/whatever you have. best is to have the knife stationary and rub the compound on there. use double sided tape.

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for a general good polish i'd say the uchi is the fastest and most user friendly. and that 3k or so finish hides scratches. its at least twice as fast as anything else imo. and its gonna look good. with good contrast. almost no skill required either to get a good result.

 

[inferno]

for a user knife that one wants to keep nice and just touch it up every month or so. i'd say uchi is the best, then maybe coticule.

for synths 800 or 2k naniwa pro.

for mirror - crox on something soft.

with all these you get fairly repeatable results. fast.

 

[Majbjorn]

Great thread! Learnt alot.

 

[Luftmensch]

Hey, that is a cool finish. Got any pictures in other light?

Better (but not brilliant) light... Shiny things are hard to photograph!

 

[naader]

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.

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!

the fingerstones could be from a hard uchi or they could be too thick. You want your fingerstones thin as possible

 

[kayman67]

I do the stone "sanding block" routine, starting with Naniwas 220 (best use of it like that) and also the scratch lines. They do actually improve food release a bit compared to "mirror" blades. I've tested this with identical knives, just finished differently.

 

[ian]

You want your fingerstones thin as possible

I’m a little confused by this, actually. I mean, I don’t really want them as thin as possible, because if you thin them to nothing then they’ll just disappear in half a minute when you start polishing. I hear people say “credit card thickness”, which makes sense. But more importantly, why do you want them so thin? People say “thin until it’s almost flexible” but it’s still stone, so I can’t imagine there’s a significant amount of flex at credit card thickness levels. It’s easier to feel in contact with the knife if it’s thin, I suppose. I think I’ve heard people say to also break the stone across the center once it’s thin, which potentially would increase the area on a convex bevel and make your work go faster. But unless you do that, I’m not sure why we are stressing so much about being thin. Other ideas?

 

[Luftmensch]

You use the thin stones for the thin knives... usubas ... And the thick stones for thick knives.

 

[ian]

Now it makes sense!

 

[valgard]

Hmm, I haven’t noticed massive dishing. Lots of mud, though. Confusing. Maybe I’m just using the stone surface more evenly than when I sharpen, so it’s less dishing and more just wearing away evenly. I’m probably not using as much pressure as you are either.

With the stone on top, I find the scratches are generally a bit deeper, perhaps because the weight of the stone translates to a lot of extra pressure.

I ended up just doing more knife on top strokes with a lot of mud to try to get it as even as possible. Then I happened to find this “fingerstone” (or would you call it a hand stone, given its size?) in my cabinet that I never use. I have no idea what it is, but it happens to work well on the hard steel! It doesn’t scratch up the finish like the others I was trying, and is making it more even. Looking forward to trying as well with some other soft fingerstones that are arriving tomorrow. I’m not really going for mirror, so I’ll probably just keep going with fingerstones for a bit and then call it done.

View attachment 87701

glue something as backing and thin that to less than 1mm thickness before using it. Finish with some powder mix with oil and a rolled cotton to smooth out the last details

I’m a little confused by this, actually. I mean, I don’t really want them as thin as possible, because if you thin them to nothing then they’ll just disappear in half a minute when you start polishing. I hear people say “credit card thickness”, which makes sense. But more importantly, why do you want them so thin? People say “thin until it’s almost flexible” but it’s still stone, so I can’t imagine there’s a significant amount of flex at credit card thickness levels. It’s easier to feel in contact with the knife if it’s thin, I suppose. I think I’ve heard people say to also break the stone across the center once it’s thin, which potentially would increase the area on a convex bevel and make your work go faster. But unless you do that, I’m not sure why we are stressing so much about being thin. Other ideas?

Stones do deform better around the small curves when they're very thin, I thought I had sent an answer here, but if you glue a backing and grind it below 1mm you can also break them by rolling them on a convex or concave surface, that allows for a much more even finish.
Regardless, you might want to smooth out the last details of the finish with some powder mix in oil, apply with a rolled cotton and go at it for a while.

 

[valgard]

Well, ***? And now the answer I sent yesterday just appeared in my new post?

 

[ian]

I thought I had sent an answer here, but if you glue a backing and grind it below 1mm you can also break them by rolling them on a convex or concave surface, that allows for a much more even finish.

Yea, that makes sense to me. Something in me is still skeptical that they deform enough to make a difference without cracking. Probably this just speaks to my inexperience, though.... Gotta keep on polishing and see it for myself now!

This knife project is on hold, though. Looks decently good atm, but I got sick of polishing it and just wanted to use the damn thing!

 

[valgard]

Yea, that makes sense to me. But I'm still skeptical that they deform enough to make a difference without cracking. Probably this just speaks to my inexperience, though, and if you say they do, then I should believe you. Gotta keep on polishing and get some experience, I suppose.

This knife project is on hold, though. Looks decently good atm, but I got sick of polishing it and just wanted to use the damn thing!

When you're back at it, do side by side testing with thick and under 1mm finger stones and you should get your own answer. I have done it and the answer is that it makes a difference for me but YMMV.

 

[valgard]

However, if the bumps and irregularities in the grind are too much I go even thinner and crack them

 

[Luftmensch]

Something in me is still skeptical that they deform enough to make a difference without cracking.

I think your intuition is correct.

I don’t really want them as thin as possible, because if you thin them to nothing then they’ll just disappear in half a minute when you start polishing.

Lets explore this function by taking it to its limit

I'll make the axiomatic statement that stone has zero flexibility. When you glue backing material to a stone, it allows the stone to crack while holding the fragments together. The thicker the stone, the larger the surfaces at the crack interfaces (resistance to moving relative to each other). As the thickness of the stone approaches zero (or the gap between stone particles becomes infinitely large) you approach the flexibility of the backing material!

Corollary: thinness has no benefit beyond ergonomics unless you are fragmenting it on a backing material

 

[valgard]

I think your intuition is correct.



Lets explore this function by taking it to its limit

I'll make the axiomatic statement that stone has zero flexibility. When you glue backing material to a stone, it allows the stone to crack while holding the fragments together. The thicker the stone, the larger the surfaces at the crack interfaces. As the thickness of the stone approaches zero (or the gap between stone particles becomes infinitely large) you approach the flexibility of the backing material!

Corollary: thinness has no benefit beyond ergonomics unless you are fragmenting it on a backing material

and cows are spheric...

 

[Luftmensch]

and cows are spheric...

to the zeroth order

 

[4wa1l]

Bumping this thread as I've started on the "fun" journey of polishing a differentially hardened 26c3 knife. Just wondering if anyone has tried using a naniwa dressing stone (600 grit) or similar to get a starting satin finish?

 

[Luftmensch]

get a starting satin finish

Satin finish isn't a precise term in this community (I don't think). I interpret it as something like a sand blasted finish (aka fake kasumi). Perhaps the subtle difference being that satin is 'frosty' and kasumi is 'cloudy'... That is just my interpretation!

Semantics aside... I havent used the naniwa dressing stone for polishing (or anything for that matter). My gut feeling is that it would be slow - which isn't necessarily a bad thing. The problem you are likely to have, is blade flatness. Since the dressing stone is a large chunk, it wont deform to any lumps and bumps on the knife surface. Unless your knife is locally flat, you may struggle to get an even finish using it. You could potentially cut a slice off and superglue it to a kitchen towel - make your own finger stone!

Are you working towards a kasumi haze... or a brushed finish? If you are going for brushed... it is far easier! You can use high grit wet & dry without worrying about knife flatness.

 

[M1k3]

or a brushed finish? If you are going for brushed... it is far easier! You can use high grit wet & dry without worrying about knife flatness.

400-~1k sandpaper leaves this kind of finish. Past 1k starts getting shiny instead of "brushed" looking.