Honyaki/hamon polishing advice.

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As some of you may know I've started making knives not too long ago. Most of them are more EDC oriented, but I recently made the dive into making kitchen knives.

Since I decided to do that I had a piece of 1095 laying around that I decided would be perfect for a 240 gyuto, and I thought just a plane 240 gyuto would be a bit boring so I differentially hardened it (plus with how hard I plan on leaving the edge, a bit of toughness towards the spine doesn't hurt).

Anyway, getting to my point. I'm planning to polish it up, and want to do my best to get a nice looking hamon line at the end. I've polished my share of clad, damascus, etc. But I haven't polished a honyaki before. If I could get any tips or tricks before I get to that point in the build it would be much appreciated.

I'm sure I have everything I'll need for the process. Various synthetics, jnats, fingerstones, I have ferric chloride, sandpaper, steel wool, etc. So whatever you guys think would get the best results let me know.
 
I'ld harden another piece of 1095 for testing, to get an idea what works for me, and to see what I like.
 
natto said:
I'ld harden another piece of 1095 for testing, to get an idea what works for me, and to see what I like.
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Not a bad idea. I only had one long bar of it that was given to me to see what I thought about it. Someone gave it to someone I know, telling them that it was supposed to be a particularly clean (I think is the word he used to describe it) batch of 1095. He had a decent amount so he gave me a billet to make something.

My plan now is to just polish it pretty high with sandpaper. Maybe even buffing compound, then dip quickly in ferric chloride, then use either my natural stones, or fingerstones. The last part is the only thing that might take a few tries.
 
Trying to polish a honyaki gyuto on bench stones would probably going to be a frustrating exercise...

I'd recommend going up to about 3k sandpaper, working as clean as possible, before switching to diamond paste for the remainder of the polish. In my (very limited) experience, the closer to a clean mirror you base polish is the more etching you can get away with without worrying about stuff like pitting during the etch. Ferric is a good place to start, but citric and/or ascorbic acid (vitamin C) will give you a brighter polish. A dip works, but I've found better control by soaking a rag in the etchant and then rubbing the etchant onto the blade. I use ammonia based window cleaner to neutralize after an etch and rinse and then follow up with soapy water to be sure. Alternating cycles of a gentle abrasive - I like Uchigumori powder, but diamond paste also works - and etching is good practice too.
 
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Take it to a high grit, as high as you can. 2-3K is enough, but you could go higher. Buffing is ok, if you remember to wipe the blade down with acetone before you start etching. Most people tend to lean away from FeCl for bringing out the finer activity, but it doesn't make a bad base etch for speeding up the process. Cycles in hot lemon juice seems to give the best results, you can start with the lemon juice but a quick 5-10 second dip in ferric chloride will save you a cycle or 3. Degrease, dip, neutralize, polish off the oxidization, repeat.

If you're looking for a more traditional look the natural stones are the way to go, but if you really want to coax every last bit of activity out of it, try 1200grit aluminum oxide powder on a wet cotton ball. The lemon juice and loose abrasive method is Walter Sorrel's hybrid method, GreenBeetle has two very good videos on YouTube about polishing hamons and they're well worth watching.

The knife that serves as my profile picture, the one attached and the one in the video link were all polished using the hybrid method. It takes about 6 hours of cycling the blade between etch and polish to get everything out of it in my experience. Getting a good polish is mostly about patience, a steady supply of bandages doesn't hurt either.

 

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Right now I'm just in the process of getting the shinogi right when I want it, I also just got the deep scratches from the 60 grit belt out from the grinder. I got decent results on the belt sander for this only being the second knife with a distal taper I've ground in, but I wanted to get the last bit of work done with stones because I have a lot more experience from thinning knives and etc.

Anyway, I'm done with shaping, and pretty much ready for the long polishing process ahead.
 
I decided to post where I'm at on the progress in case anyone is curious.

This is after a quick test dip in ferric chloride.
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Don't worry. I'm very aware I still have quite a bit of polishing ahead of me.

This particular knife has been a big reminder that I need to restock my higher grit sandpaper. I usually leave a satin finish on the knives I make, which is more practical for a knife that will be used. So I don't tend to go above 600. I've done plenty of mirror polishing in the past so I I have all the way up to 10000 grit, but I'm pretty much out of the stuff in the 600-1200 range, which always seems to be what runs out for me, then I forget to replace it. I'm making it work with what I have though.
 
I do really like how that banding looks in the first picture, right where the peaks of the hamon go towards the edge. I really think some great detail will come out of this when I actually get done polishing. It goes to show you can get great detail in a hamon using parks 50, rather than water.
 
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jwthaparc said:
As some of you may know I've started making knives not too long ago. Most of them are more EDC oriented, but I recently made the dive into making kitchen knives.

Since I decided to do that I had a piece of 1095 laying around that I decided would be perfect for a 240 gyuto, and I thought just a plane 240 gyuto would be a bit boring so I differentially hardened it (plus with how hard I plan on leaving the edge, a bit of toughness towards the spine doesn't hurt).

Anyway, getting to my point. I'm planning to polish it up, and want to do my best to get a nice looking hamon line at the end. I've polished my share of clad, damascus, etc. But I haven't polished a honyaki before. If I could get any tips or tricks before I get to that point in the build it would be much appreciated.

I'm sure I have everything I'll need for the process. Various synthetics, jnats, fingerstones, I have ferric chloride, sandpaper, steel wool, etc. So whatever you guys think would get the best results let me know.
Click to expand...

To best predict the potential a piece of 1095 has to make a really flashy and awesone hamon you need to look at the steel's heat sheet and check how much manganese was in that batch of steel . Manganese is the mortal enemy of hamon formation in high carbon steels. So a batch of 1095 with more incidental manganese has less potential to form a nice hamon pattern than a batch with less manganese. During the hardening process the steel gets heated beyond its austentitic temperature it loses much of its room temperature crystaline stucture and is free to find a more relaxed, uniform and less stressed structure if it cools slowly enough But thats no fun so we quench it quickly. Any that gets suddenly quenched (like the edge) doesnt et a chance to relax The crystaline structure forms forms whether thing like carbon fit in the structure or not. And this causes the hardness everybody wants. That hardened crystaline structure in srteal is called martensite. Everthing on the hard side of the hamon line is martensite . Where the steel has enough time to cool gracefully and relax there is a very different structure that is called ferritic . The Martensite structure and the ferritic structure do not agree on building codes or property lines at all/ The place where these two meet and struggle for control is visible to us on a macroscopic level as the hamon line .
 
mikaloyd said:
To best predict the potential a piece of 1095 has to make a really flashy and awesone hamon you need to look at the steel's heat sheet and check how much manganese was in that batch of steel . Manganese is the mortal enemy of hamon formation in high carbon steels. So a batch of 1095 with more incidental manganese has less potential to form a nice hamon pattern than a batch with less manganese. During the hardening process the steel gets heated beyond its austentitic temperature it loses much of its room temperature crystaline stucture and is free to find a more relaxed, uniform and less stressed structure if it cools slowly enough But thats no fun so we quench it quickly. Any that gets suddenly quenched (like the edge) doesnt et a chance to relax The crystaline structure forms forms whether thing like carbon fit in the structure or not. And this causes the hardness everybody wants. That hardened crystaline structure in srteal is called martensite. Everthing on the hard side of the hamon line is martensite . Where the steel has enough time to cool gracefully and relax there is a very different structure that is called ferritic . The Martensite structure and the ferritic structure do not agree on building codes or property lines at all/ The place where these two meet and struggle for control is visible to us on a macroscopic level as the hamon line .
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That's a pretty good simplified explanation of it. So any advice on polishing one?
 
jwthaparc said:
That's a pretty good simplified explanation of it. So any advice on polishing one?
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Heck no! I go mad just trying to sort out some sort of understandable way o compare the various ways that knife industry suppliers schenes to name and number the abrasives they provide to us in ways that prevent any comparison or navigation through their products. If I was forced to try using their voodoo grindersnd pastes in way that ended up with a blade tat reflectd like a mirror and a proud hamon... it would probably end me

I had less trouble understanding and confidently maneuvering through puberty than Ive had when studying this chart https://cdn.shopify.com/s/files/1/0984/5900/products/GLGC_2000x.jpg?v=1640812934
 
mikaloyd said:
Heck no! I go mad just trying to sort out some sort of understandable way o compare the various ways that knife industry suppliers schenes to name and number the abrasives they provide to us in ways that prevent any comparison or navigation through their products. If I was forced to try using their voodoo grindersnd pastes in way that ended up with a blade tat reflectd like a mirror and a proud hamon... it would probably end me

I had less trouble understanding and confidently maneuvering through puberty than Ive had when studying this chart https://cdn.shopify.com/s/files/1/0984/5900/products/GLGC_2000x.jpg?v=1640812934
Click to expand...
Lol. Well glad you added an nice explanation for those who don't know what is going on with differentially hardened knives. In particular ones that have the correct properties to show good contrast between the pearlite, and ferrite, and the martensite, and where they intermingle in the middle.
 
I’ve found paper above 3k - 5k grit to be too slow. I’d recommend diamond paste applied with hard felt from that point up to whatever level of polish you desire. Much faster and more consistent in my experience.
 
ethompson said:
I’ve found paper above 3k - 5k grit to be too slow. I’d recommend diamond paste applied with hard felt from that point up to whatever level of polish you desire. Much faster and more consistent in my experience.
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Ok. Good to know. I'm getting close to that point. I'm around 2000 now. I keep checking if I have a fine enough polish to go over to the buffing wheels on my bench grinder every grit, so I can continue with my progression from there, but so far 1500 hasn't been high enough to let even my coarsest polishing compound take out the scratches. I'm really hoping 2000, or 2500 will be the highest I end up having to hand sand.
 
Do you guys think I can get a good looking result with something like a very fine satin finish on the hardened steel? Maybe 800, or 1000 grit. Taking extra care to keep the scratches going in the same direction, and uniform.

I'll be honest, I'm asking because I'm tired of polishing 😫 lol. Not so much the actual getting to a mirror part is, but I set it down and something scratched it, or idk what happened but there are a few stray marks, and it looks like I'm going to have to go back down from 1500, to something lower (hopefully not 800 again) to get whatever caused it out. Also I'm pretty much out of 1000 grit paper, so I'm really trying to avoid doing that. Idk.
 
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My pain exactly when polishing the honyaki I was working on and finished. It is the most difficult and painful knife related thing I did -- but I also thinned it too, which made it extra difficult. Of course, some knife makers do this too. . .

Depends what you want -- I had a good working finish with 320 grit #M sandpaper and 220 grit SiC powder, and a WD 40 and a 5mm thick foam pad to back the sandpaper, which you can find in my thread about it. Polish with metal polish after and it should be good. Here it is before the metal polish after the sandpaper combo

The resulting finish had really shallow scratches . . . around 2K-3k from a synthetic stone.

159609-PXL-20220314-004847200.jpg
 
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Ok good to know. I'm going to try polishing with my uchigumori, and see if that can get out some scratches. If not I'll drop down to a lower grit.
 
I just saw a post on this yesterday from a guy working with Salem Straub. He did a 600 grit sandpaper finish, FeCl dip, I think 1200 grit sandpaper, degrease another dip and then 5k sandpaper finish. I think I am remembering that correctly. It looked great when he was done. Not exactly mirror finish but a great hamon.
 
Matt Jacobs said:
I just saw a post on this yesterday from a guy working with Salem Straub. He did a 600 grit sandpaper finish, FeCl dip, I think 1200 grit sandpaper, degrease another dip and then 5k sandpaper finish. I think I am remembering that correctly. It looked great when he was done. Not exactly mirror finish but a great hamon.
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That's interesting. I know ferric chloride will actually sort of chemically polish steel, by eating away the peak of the scratch pattern. So it could help with going between grits.

I may try doing the multiple dip technique.
I just went back to polishing on my jnats. It looks like it's working well with the polish I already have set up. So hopefully I can move forward with this project soon.
 
I took a couple flattering pictures of the bunka I'm working on. In real life there are still scratches that need to be removed. It's like deeper accidental scratches happen so easy. But when you try to polish harden steel on purpose it doesn't want to react to the abrasives. Anyway, day 1000 of the polishing stage is over.
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Oh btw this is after etching, then polishing with a few things then going to the buffing wheel, under the false hope that maybe this time would be the time the scratches where fine enough.


Maybe I need better compound?
 
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