KU rubbing off

[fortheloveofmoar]

Newbie question probably but here we go. Not sure what to do, if anything about the Ku finish rubbing off. I’m just using a napkin with some tsubuki oil on it and it seems to be rubbing off.

Rubbed it down good like a cucumber washing and it seems to be diminishing.


should I do anything about it? I assumed it not harmful.

(note I know it’s not a fault or anything of the knife so not trying to suggest some kind of defect)

 

[Simply]

Depending on how it’s applied or forged, it’ll happen. Some are robust and near bulletproof, others will vanish with normal light sponge washing.

 

[Simply]

Believe it or not this is a KU TxK

 

[Carbonara]

Newbie question probably but here we go. Not sure what to do, if anything about the Ku finish rubbing off. I’m just using a napkin with some tsubuki oil on it and it seems to be rubbing off.

Rubbed it down good like a cucumber washing and it seems to be diminishing.


should I do anything about it? I assumed it not harmful.

(note I know it’s not a fault or anything of the knife so not trying to suggest some kind of defect)

Mr Jiro would like to have a word with you

 

[dehory]

This is what mine looks like with use – much, much lighter than yours, but some of the black still remains and doesn't rub off with an oiled paper towel.

 

[Dave]

Nah dude that is defective and will look like absolute dogsh*t by the time you're done cleaning it. I can provide you with an address to send it to be properly disposed of...

 

[PeterL]

Mr Jiro would like to have a word with you

This was the first thing I thought of when I saw the post. Was actually surprised to see it wasn't a Jiro

 

[cheeksfullwalletempty]

Well, it IS completely normal for the ku finish to wear off a bit, especially with regular use. The ku finish is essentially a patina that gives the knife its character, but over time it can diminish. There’s nothing wrong with that; it’s a natural process. Using tsubaki oil is a great way to maintain it, but try to be gentle while cleaning. Instead of a hard material, it’s better to use something soft, like microfiber. However, having seen your pic, it just doesn't look right. I dont think it should be coming off THAT much.

 

[Corradobrit1]

This was the first thing I thought of when I saw the post. Was actually surprised to see it wasn't a Jiro

You and me both. Was expecting, help my $1200 Jiro Ku is melting and is now a migaki.

My Kato Ku and Denka have never diminished in over 7 years of constant use. I don't use a scourer though.

 

[fortheloveofmoar]

@milangravier - I know I’ve seen you do a few things with Ku, maybe once or twice . I’ve seen you scrub your KU really hard without change. Any insight on how you achieve that kind of super stable finish? ( just curious)

 

[Bico Doce]

@milangravier - I know I’ve seen you do a few things with Ku, maybe once or twice . I’ve seen you scrub your KU really hard without change. Any insight on how you achieve that kind of super stable finish? ( just curious)

You can’t be asking him to disclose his trade secrets!! There’s not much you can do after the fact. Just accept the fate of your knife

 

[fortheloveofmoar]

Haha good point disregard Milan.

I know there isn’t anything to do after making just curious.

 

[blokey]

View attachment 356169

Believe it or not this is a KU TxK

*was

 

[kdizzog6]

The ku is also great as a seasoning when it rubs off on your food.

 

[Simply]

*was

A distant memory of ku

 

[milangravier]

Hey,
I don't need to say what I am doing to give you a little more information.
About Ku that rub off or not : it's simply that everybody use the word kurouchi to tell when there is black color on the blade but there is actually different way to bring that dark color on a blade and some are just a little coat that will rub quite easily, some are strong coat that won't rub off easily

Common black finishs :
- burnt oil, I think the most common : if you quench your knife in the oil you can make some kind of seasoning and have some black burnt oil finish on the blade. That finish will rub off pretty easily. As much as seasoning should be food safe, I am not really sure about synthetic quenching oil seasoning...
- etching can do it : if the blade is hard steel, you can polish the hammered part and etch it, you will get a black finish : again it will rub off easily as it is very shallow.
- I bought two japanese knives in my life, one from mutsumi hinoura that had a weird black finish. it could be burnt oil finish maybe but maybe other ways are possible. Can be rubbed off also, less easily than some others but still it is not looking like sclale. Just to say, even in japan it can be not proper kurouchi. (picture attached is that hinoura blade next to one of mine)
- gun blueing : not food safe but it can create chemically a black finish.
- less common but rust blueing exists : you can make some iron to rust evenly and then convert rust iron oxide into black oxide (hematite if I am not saying it wrong). That how japanese sword's tsuba are often finished.
- and maybe other ways.
- finally : kurouchi (because I think that's the name of that technique and other ways should be called black finish). It is forge scale, iron scale made through the heat of the blade to at least 700 degrees celsius. It's iron oxyde (hematite again) created by the heat of iron. If you can control it you can make it appears on the all blade evenly, thick enough and well attached to the metal so it won't flake or be rubbed off. It is very solid and even with stones like 200 grit stones I can see I can scratch it but not getting it off, so it is really solid. Not invincible though, you can of course getting rid of it : or you just grind through it, or you let the blade for a day in strong vinager and it will melt the kurouchi.

 

[jedy617]

Milan with the goated information is always. The big write ups are so nice, I always go back to reference some of your stone write ups

 

[fortheloveofmoar]

Wow @milangravier with the absolute knowledge bomb

Please, let me support you and buy one of your Ku knives . I love Ku and you have the best I’ve seen

 

[Hz_zzzzzz]

Milan explained it pretty well and yours look just like the burnt oil seasoning on my carbon steel pan. I would rub them off as much as possible as we don’t really know if it is food safe.

 

[Jovidah]

This is what happens when you sit there fondling it like Gollum while whispering 'my precious' for 6 hours a day...

 

[NotAddictedYet]

My BB x Dalman.

When I got it 2nd hand, the black stuff would rub off onto towels. I was pretty surprised since none of the other "kurouchi" knives I had did that.

Some of it still remains but is no longer rubbing off.