# Remove KU and refinish with cloudy finish?



## CiderBear (Aug 6, 2019)

Hi all, 

A couple days ago I got a one off Watanabe iron clad Nakiri in white steel. The cladding is very reactive - this is what it looks like after 3 meals











However, I'm not into the KU finish on this - it's very blotchy, and completely different from the KU on his Wat Pro nakiri in Blue steel. 

I would like to remove the KU finish, and if possible refinish the entire blade in a finish similar to the part that already has patina - I'm guessing this is called a kasumi finish? 

I currently have a Gesshin 1000/6000 combo stone, and some wet sandpaper. 

I would be grateful if you experts could chime in on how I should go about doing this. Some fine folks have given me advice on the "Show your newest knife buy" threads, but I didn't want to clog that thread with follow up questions, so I thought I would make a separate thread here. 

Some bonus questions:
1) Any idea why the KU finish is so blotchy on this knife? There are patches of KU in blue color, so I'm not sure if this is related to the KU process or what. 
2) Anyone has advice on how to polish the horn ferrule? It has a sweet half blonde half black ferrule, but it doesn't look as nicely polished as the horn ferrules on my Kochi and Hinoura. 

Thank you!


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## daveb (Aug 6, 2019)

I personally think that the post kurochi finish looks like crap whenever I've seen it done. But some folks like it. IIRC it's a matter of some BKF and some scrubbing to get it off. Maybe some sandpaper for the reluctant bits.

And. Any potential resale value will go down the tubes. Perhaps press the Easy button and move it along as is?


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## ian (Aug 6, 2019)

I don’t get it. What’s the reason a removed KU finish looks bad? Do people just not take it far enough? I mean, if you really wail on it eventually you’ll just have a polished finish, right?


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## McMan (Aug 6, 2019)

ian said:


> I don’t get it. What’s the reason a removed KU finish looks bad? Do people just not take it far enough? I mean, if you really wail on it eventually you’ll just have a polished finish, right?



Yes and no... depends on the knife. KU can hide a multitude of sins. Removing it brings them to light. I tried on a Moritaka. I was happy with how it came out, but it took forever by hand (even with low grit) and then took forever to get looking nice enough. The KU hid file marks, a few deep pits, etc... these only became noticeable after the KU came off. Power tools would be easier. 

Long story short, it won’t look identical to an iron-clad knife. I’m with DaveB—if it bothers you, sell it and try again.


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## nutmeg (Aug 6, 2019)

Yes. Watanabe nakiri are already thin. 
It will take ages, not sure the finish will be good looking and the knife will lose value.
I wouldn‘t do it.


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## CiderBear (Aug 6, 2019)

Honestly, I bought the knife without intending to sell it anyway. Out of all my knives, this is probably the one I'm most comfortable experimenting with, hence the question.


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## pkjames (Aug 6, 2019)

i have done it before on a shigefusa KU. It takes a very long time and the end result is not as nice as you would like since the blade is likely not very flat and there are spots where you just can't get rid of (get to).


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## milkbaby (Aug 6, 2019)

I think it looks cool the way it is. The evolution of the KU finish tells a story similar to the way the evolution of the patina does on the blade road.

I don't know the source of the cladding he used, but it could vary in quality and be non-homogenous so you get different colors across it? There's supposedly some type of blackening that Japanese bladesmiths use on KU finishes sometimes, but I don't know what that is, could be similar to cold bluing solution used on firearms which is known to be very prone to inconsistency and blotchiness.

Guessing it's as-forged, so when you try to sand it down, you'll reveal all the high and low spots and could take forever to get it even as everybody else suggested. If you have a friend with a sandblasting cabinet, that is probably the quickest way to remove all the KU.


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## ojisan (Aug 6, 2019)

I have a similar looking knife I bought at eBay for $10 and was wondering what made such an uneven KU finish. It's blackened by some sort of bluing liquid?

Anyway, KU knives tend to have uneven surface as well. It can be hell to polish it.


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## childermass (Aug 7, 2019)

I‘m going to tackle the horn ferrule polishing question:
I use a dremel like tool with a felt brush and a beeswax based furniture polish for this. This combination takes the ferrule to high gloss polish in no time.
I guess this will also work by hand with a clean cloth but will take some serious rubbing to accomplish.


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## stringer (Aug 7, 2019)

Here are two attempts I have worked on that had badly damaged kurouchi finishes. I don't have before pictures. I already did quite a bit of work on them to get them to this state of presentability. To make them "pretty" would require a lot more.

The first is a santoku. I used a dremel with some kind of little attachment I don't remember but you can see the marks it leaves if you look close. I smoothed it over a bit with sandpaper and then did the bevel polishing with stones. It had a hammered texture underneath the kurouchi. This was also my first wa handle attempt. Horn ferrule with curly maple. 






Here's a Chinese cleaver. This one is all sandpaper. I put this handle on it (spalted sycamore) and then decided a year or two later that I wanted to remove the finish and redo it. It made gettting rid of the kurouchi near the bolster very difficult. I left it pretty rustic. I wish I had before pictures. 






Anyways, it's your knife. Do what you want to it. Have fun. Be safe. Show us pictures.


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## CiderBear (Aug 7, 2019)

Thank you all again for your help. I was under the assumption that KU finish on top of nashiji finish would be difficult to work on (like @stringer's 2 knives), but a flat/ smooth KU finish like Watanabe or Shig might be better. 

It seems like I was wrong - as @pkjames did with his Shig and @milkbaby suggested - what's underneath my KU finish my not be smooth. @childermass what was your experience with removing the KU from your Wat Standard nakiri? Were there obvious high/ low spots?

As you can see from the knife, there are "forging marks" (not sure what to call them) near the spine, around the kanji. If I do remove the finish, I will try to leave that part alone. Watanabe has some one-off knives he calls "gabi gyuto/ petite" that seem to have a polished blade except for the areas near the spine https://www.kitchen-knife.jp/special/damascuschefknife.htm[URL]https://www.kitchen-knife.jp/special/damascuschefknife.htm [/URL]- I'm wondering if he left the KU there for the same reason?


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## kayman67 (Aug 7, 2019)

I've done a few. It's really hard to know what you find. Some were better than others for sure. There is so much work involved and I only did those due to some type of damage.


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## inferno (Aug 7, 2019)

if you dont like it just grind it off. I suggest a small orbital sander. I have a small blue bosch. and it would eat that away in a few minutes. Or get a few sandpapers. probably gonna take a few hours to get to stringers look if doing this by hand unless its a smooth surface under there.


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## childermass (Aug 7, 2019)

CiderBear said:


> @childermass[/USER] what was your experience with removing the KU from your Wat Standard nakiri? Were there obvious high/ low spots?



The Kurouchi on this particular knife sanded off very easy, it just took a few minutes to get rid of it. The surface of the blade was nowhere near even though. It had something more like a Nasiji look as with stringer's blades, just not that pronounced, plus some hammer marks. The Nashiji effect is due to lots of small pores in the cladding and it's almost impossible to get the Kurouchi out of those. As I liked the way it looked I left it this way and sanded it finer to make it look nicer. Evening out everything to achieve a smoooth and somewhat polished finish would have taken very long and would have meant to sacrifice a lot of material.
If you are fine with a little rustic look, it would be worth a try to see what's underneath the Kurouchi. Unfortunately this can't be reversed and as daveb and nutmeg already mentioned will have an impact on the resale value of the knife.


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## panda (Aug 7, 2019)

i did it to a takeda because the KU had worn out a lot. it looked absolutely horrendous, do not recommend.


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## JoeWheels (Aug 7, 2019)

Ku finishes seem to wear off eventually w regular use. 
Unless the knife is precious, why not move in that direction to clean things up?
Wabi Sabi.

Here are a few from my kitchen w ku removed.
The gyutos came used w ku partially gone, and I simply cleaned them further.
The others I hit w the stones, sandpaper, etc., leaving just enough for that rustic look.
Never looked back. They all slide through food w less drag now too.
Looks are subjective, right?


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## childermass (Aug 7, 2019)

JoeWheels said:


> View attachment 58419



I like these a lot, especially the third and fifth from the left.


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## JoeWheels (Aug 7, 2019)

Third from left is Yamashin funayuki.
Fifth from left is Matsubara B2, one of my favorite knives.
Makes me laugh when I hear folks disparage small knives.
These 2 fly.


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## childermass (Aug 7, 2019)

JoeWheels said:


> Third from left is Yamashin funayuki.
> Fifth from left is Matsubara B2, one of my favorite knives.
> Makes me laugh when I hear folks disparage small knives.
> These 2 fly.



I totally agree, my 135mm Yuki Bunka is one of my favorite knives.

Sorry everyone for being off topic, I will stop it now [emoji4].


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## CiderBear (Aug 7, 2019)

@childermass no, it's fine! Thanks again for sharing your experience with me!


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## milkbaby (Aug 7, 2019)

It's natural the KU should be uneven surface because it's typically forge scale from forging and heat treatment (dark oxides that form on the surface). Some western knifemakers think it's ugly and a shortcut because the bladesmith doesn't take the time to grind the entire blade to a consistent surface and finish, and it's true a KU knife is usually just forged and the bevels ground without extensively evening out the surface. Compare that to a Konosuke Fujiyama where the entire surface has been meticulously finished leaving no traces that it was ever forged (except for the wavy lamination line on the clad knives).

The problem with forging is that you can easily have a hammer strike that goes deeper than intended. Then when you try to grind everything even, the low spot will be too low, i.e. if you try to grind it out, then the knife will get too thin, so then you just leave it.


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## kayman67 (Aug 8, 2019)

Let me show you some worse/best case scenario I have right now. And you don't always know until it's too late.


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## CiderBear (Aug 8, 2019)

Thank you @kayman67 and @milkbaby. I really appreciate your advice! I'll have to sleep on it before I decide what to do, then


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## SilverSwarfer (Aug 10, 2019)

Here’s a Takeda “Yanagi” with removed KU. I kinda like it! My opinion for utility purposes: it seems silly to tiptoe around preserving a finish as if the tool were BNIB. But I’m way more favoring of the performance end of the performance vs presentation spectrum. Obviously there’s risk of imperfection revelation when a KU is removed (I think that’s part of what KU is all about), but I see the imperfections as birthmarks of the knife.


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## dwalker (Aug 10, 2019)

I'm pretty sure a nashiji finish is a KU that has been media blasted by the finisher. Most of the readily available nashiji finished knives are stainless clad, but you could try that if you wanted. This way, the low spots won't matter and will be blasted clean. Keep in mind it will readily patina.


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## M1k3 (Aug 11, 2019)

SilverSwarfer said:


> Here’s a Takeda “Yanagi” with removed KU. I kinda like it! My opinion for utility purposes: it seems silly to tiptoe around preserving a finish as if the tool were BNIB. But I’m way more favoring of the performance end of the performance vs presentation spectrum. Obviously there’s risk of imperfection revelation when a KU is removed (I think that’s part of what KU is all about), but I see the imperfections as birthmarks of the knife.
> View attachment 58632
> View attachment 58633
> View attachment 58634



I really like the look of that!


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## SilverSwarfer (Aug 11, 2019)

Thanks for the feedback. This is actually the easiest maintenance knife I have ever had, in terms of keeping it looking good. Surface texture automatically eliminates worries about scuffs or stains. When it’s time to polish, I can be as aggressive as I want since scratch patterns are totally obscured.


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## Foltest (Sep 7, 2019)

Ferric chloride works well for kurouchi removal. I wanted to have even surface texture on this blank https://www.dictum.com/en/for-japan...lack-forged-skin-3-layers-gyuto-180-mm-719591, so I soaked it for 10-15 minutes. Kurouchi completely dissappeared. Imo this is better than sanding it, takes less time and resulting finish was very nice (even surface, no scratch marks).


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## CiderBear (Sep 21, 2019)

Quick update: I finally did it. I removed the KU using Bar Keeper's Friend and a green scratch pad. I like the knife a lot more now.











I have yet to polish the horn ferrule though. Is it something I can do by handle, because I don't have any special tools to use...


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## ian (Sep 21, 2019)

Hey, that came out nice!


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## CiderBear (Sep 21, 2019)

Yeah, much better than what I expected based on how the KU looked. Do you think it means the KU might have been chemically applied and not leftover scale from the forging process?


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## Midsummer (Sep 21, 2019)

Amazing how doing that kind of work gives you a sense of ownership. You no longer fear really messing it up. 



CiderBear said:


> Yeah, much better than what I expected based on how the KU looked. Do you think it means the KU might have been chemically applied and not leftover scale from the forging process?



Not an expert; but chemical KU's are definitely a thing.


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## dafox (Sep 21, 2019)

I polished some horn ferules using a drill, a cotton buffing wheel, and white jewelers rouge, they came out very nicely. Got the wheel and rouge at Ace Hardware.


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## SilverSwarfer (Sep 22, 2019)

@CiderBear - looks great! I hope it serves you nicely; I think you’ll find it’s rather low maintenance.


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## SilverSwarfer (Sep 22, 2019)

Midsummer said:


> Amazing how doing that kind of work gives you a sense of ownership. You no longer fear really messing it up.


+1 —> huge! This is absolutely true


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## miggus (Sep 22, 2019)

Ah, that came out nice! Thanks for sharing.

I've been thinking about doing the same to my Moritaka Nakiri. What stopped me so far is the fact that it is ironclad and the cladding is much more uneven than your knife.


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## CiderBear (Sep 24, 2019)

Thank you @miggus @Midsummer and @SilverSwarfer
Yeah it actually came out a lot better than expected. There was a low spot in the blade road near the heel that I only noticed when I tried to make it look kasumi-ish. Grinding that out with a 1000 grit stone (I only have a Gesshin 1000/6000) was... not fun. I'm actually impressed how dark i can the blade road to look with the 1000 side of the G1/6k though. Makes me want to try Jon's Jinzo Aoto so much more.

Any advice on what I should do with the blade face? It looks pretty matte atm, I'd like it to be a bit shinier, I think. I'm thinking sandpaper, but I'm not sure which grid to get.

@dafox thanks. It sounds like I need some sort of tools for the horn, then. I bought this kit Dremel 684-01 20-Piece Clean & Polish Rotary Tool Accessory Kit With Case https://www.amazon.com/dp/B00005LEXV/ref=cm_sw_r_cp_apa_i_.bJIDbPSNFZ57 thinking that I could use it outright, but no, I need a Dremel tool to attach it to. Damnit


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## SilverSwarfer (Sep 24, 2019)

I’ve had some easy success with 0000 steel wool and Autosol or Simichrome if you’re aiming for shiny. Autosol “original” formula has some abrasive you can feel during polishing while Simichrome seems finer. I’d recommend getting both, especially if you like the shiny things (like me: I’m not a patina guy)! Aside: you don’t really need the steel wool, i just have an easier time of i develop any pesky rust spots.


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## childermass (Sep 24, 2019)

CiderBear said:


> I bought this kit Dremel 684-01 20-Piece Clean & Polish Rotary Tool Accessory Kit With Case https://www.amazon.com/dp/B00005LEXV/ref=cm_sw_r_cp_apa_i_.bJIDbPSNFZ57 thinking that I could use it outright, but no, I need a Dremel tool to attach it to. Damnit



Try to use it with a normal drill, this should work just fine. Maybe use another piece for practice until you get a feeling for it. Or take it as an excuse to buy a dremel [emoji23].


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## ian (Sep 24, 2019)

For sandpaper, you can just get 

https://www.amazon.com/Sandpaper-As...ateway&sprefix=automotive+sand,aps,140&sr=8-4 

or something. $13, many many grits.


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## suntravel (Sep 24, 2019)

Removing KU works well with citric acid dissolved in hot water, the stuff used for cleaning coffee machines...

.. learned that by mistake, added some in coffee mixture for a forced patina, and the KU was history 

Regards

Uwe


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## ian (Dec 1, 2019)

Used to look like this:






Haven’t finished with the polishing, obviously, but removing the KU wasn’t a big deal. Took at most 30 min with 220 grit sandpaper, and the grind underneath was just fine. Cleaning up the scratches takes a while, of course. Given that the cladding is stainless, what’s the point in giving it such an awful looking KU finish? It looked even worse in person.


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## CiderBear (Dec 2, 2019)

@ian does it mean that Watanabe's KU finish is chemically applied afterwards, and not a byproduct of the forging process?


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## Nemo (Dec 2, 2019)

Nice job


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## ian (Dec 2, 2019)

CiderBear said:


> @ian does it mean that Watanabe's KU finish is chemically applied afterwards, and not a byproduct of the forging process?



Yea, I’m assuming so, but I don’t know. It sure looks different than other KU and I’ve heard people talk about him using a ‘blueing agent’ or something. Seems unlikely that the grind would be so good if it was real, but what do I know. In contrast. I’m doing another KU removal on a knife I bought for $30 on BST, and this is requiring basically a complete regrind of the knife....

Btw, on the Wat above I couldn’t use stones on most of it due to concavities in the grind. On both Wat’s I’ve owned, the blade road on the back of the knife has been slightly concave, and on this one there’s a shinogi “ridge”, ie the front face of the knife above the shinogi line is also slightly concave.


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## Carl Kotte (Dec 2, 2019)

The shinogi does look a little wobbly right? Like this smiley [emoji37]


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## ian (Dec 2, 2019)

Yea, it is wobbly for sure. You can see the same wobbles with the KU, but it might be more noticeable without. Doesn't bother me much, though. The Mizuno I have also has a kind of wobbly shinogi, but they must tape off part of it when they finish it, because OOTB the (differently finished) blade road makes it look like the shinogi is impossibly perfect. 

Anyway, if it ends up bothering me I'll refinish it in a way that you can't really see the shinogi.

I'm kind of confused by wobbly shinogi lines, though. Presumably, these knives are ground all over (the Miz at least), so how do you get a wobbly line?


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## Carl Kotte (Dec 2, 2019)

Beats me!


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## marc4pt0 (Dec 2, 2019)

You can do this by hand. Just use fine grit sand paper, and micro mesh pads if you have them


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## ian (Dec 7, 2019)

Here’s the most recent polish on the formerly KU Wat. 




I straightened out the shinogi line (more or less) and gave it a bit more distal taper, while flattening the part above the shinogi. There are still some concavities above the shinogi, and the geometry is irregular above the shinogi near the handle. However, I like how it’s real thick near the handle, and I imagine the slight concavities will contribute somewhat to food release, so I didn’t mess with them as long as they were far enough above the shinogi. Also rounded the spine and choil. This is also my first real kasumi. Not perfect, but ok!

Anyway, it looks incomparably better than when it had the awful kurouchi.

Edit: also, this was my 1000th post!


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## 4wa1l (Jun 24, 2021)

Does anyone know if there's a suitable dremel attachment that can remove small spots of kurouchi that lay inside indentations? I've sanded most of the kuro off a couple of knives but each have a few remaining deeper spots that I'd like to remove. Not looking for an even metal finish and honestly don't mind if there are still a few spots left, just not a fan of rough kuro finishes.

I was thinking something that isn't extremely abrasive, maybe a wire brush attachment? Or any other ways to do it short of FeCl3?


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## nakiriknaifuwaifu (Jun 24, 2021)

4wa1l said:


> Does anyone know if there's a suitable dremel attachment that can remove small spots of kurouchi that lay inside indentations? I've sanded most of the kuro off a couple of knives but each have a few remaining deeper spots that I'd like to remove. Not looking for an even metal finish and honestly don't mind if there are still a few spots left, just not a fan of rough kuro finishes.
> 
> I was thinking something that isn't extremely abrasive, maybe a wire brush attachment? Or any other ways to do it short of FeCl3?


Perhaps a felt wheel would be a good option. I have heard it being used to clear the black stuff from rust pitting.


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## childermass (Jun 24, 2021)

4wa1l said:


> Does anyone know if there's a suitable dremel attachment that can remove small spots of kurouchi that lay inside indentations? I've sanded most of the kuro off a couple of knives but each have a few remaining deeper spots that I'd like to remove. Not looking for an even metal finish and honestly don't mind if there are still a few spots left, just not a fan of rough kuro finishes.
> 
> I was thinking something that isn't extremely abrasive, maybe a wire brush attachment? Or any other ways to do it short of FeCl3?


There is also a brass wire brush wheel that works well. It's sually soft enough to not visibly scratch the steel.


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## RDalman (Jun 24, 2021)

4wa1l said:


> Does anyone know if there's a suitable dremel attachment that can remove small spots of kurouchi that lay inside indentations? I've sanded most of the kuro off a couple of knives but each have a few remaining deeper spots that I'd like to remove. Not looking for an even metal finish and honestly don't mind if there are still a few spots left, just not a fan of rough kuro finishes.
> 
> I was thinking something that isn't extremely abrasive, maybe a wire brush attachment? Or any other ways to do it short of FeCl3?


If it's scale in a forged surface, yes wirewheel is good. Other options are sandblasting or acidbath (hydrochloric)


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## 4wa1l (Jun 24, 2021)

Thanks for the help everyone! I'll get a wire brush and try a felt one too. I want to avoid any wet chemistries at this stage. 

Will report back with results.


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## childermass (Jun 24, 2021)

Maybe needless to say but use protective glasses when using the wire wheel in case some of the wires break off it’s better to not have them hit your eyes.


4wa1l said:


> Thanks for the help everyone! I'll get a wire brush and try a felt one too. I want to avoid any wet chemistries at this stage.
> 
> Will report back with results.


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## 4wa1l (Jun 24, 2021)

childermass said:


> Maybe needless to say but use protective glasses when using the wire wheel in case some of the wires break off it’s better to not have them hit your eyes.


Always good to say it. I've had one of the small cutting disks break on me in the past which could've been nasty.


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## geoff_nocon (Jun 24, 2021)

Definitely worth doing if you put the time and effort heres my watanabe petty. Did not do any of the heavy lifting though. Only thing i did was polish and gave it a kasumi finish. 








Was initially done by nutmeg but it still had the wide bevel shoulders so i gave it to dave for thinning. Now it just goes through anything


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