On CCK carbon steel, reactivity, and patina

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Schnabelhund

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Long time no see!

Three years ago, I asked a few questions about CCK carbon steel knives and thanks to your support, I took the plunge and decided to get my first carbon steel knife while I was in Hong Kong. When I told my local host that I was planning to buy a CCK knife, he decided to gift me a large slicer :)

It was my first (and to this day only) carbon knife, and I was amazed by its sharpness, but I noticed a sulfur-like smell and some discoloration of foods while I was using it for the first time. Therefore, I decided to force a patina onto it and turned the blade black with an oxalic acid solution. I've never had any issues with reactivity since and the CCK slicer turned all my other knives into benchwarmers.

The other night, somehow a few drops of water made it onto the blade, ate through the patina, and left rusty spots on it. I decided to remove the rust and polish the blade before I force a patina onto it again. The thing is, now that I see the shiny bare steel blade, I kinda like the look.

I know Japanese chefs like to keep their carbon knives shiny and patinaless. Surely they would prefer having patinas if their knives made their food smelly and spotty, wouldn't they? So how do they deal with this issue? From lurking around here, I vaguely remember reading that CCK carbon blades are particularly reactive and that nicer, more expensive carbon steels don't have this kind of issue. Is this the case?

I know many of you would just use the knife and allow a natural patina to develop, but natural is not the appearance I'm after. I'd like to either have a shiny bare blade or a dark, matte, uniform patina all over the blade. Now I can think of three ways to go forward.

1) Force a patina onto the blade again. The previous dark one served me very well for three years and I didn't hate the look.

2) Find out how Japanese chefs keep the blade shiny and at the same time deal with the reactivity, then try to do that. I do like the look better (for now).

3) Somehow periodically renew the (hopefully food grade) protective lacquer the knife had OOTB.

If you have any advice, it'd be much appreciated!
 
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Pie

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I noticed CCK steel is quite reactive. I think mine has something to do with the grind marks - heavily textured from the grinding process, no polish to speak of. My guess it that water/moisture tends to hide in the rough finish, providing a better environment to produce rust than a nicely polished surface.

Personally I don’t mind too much, as I only use it for butchery and the rare occasion something huge needs to be broken down. It’s not so pretty of a knife that I can’t just rub off the rust with some stone mud.

A different angle to your options would be to polish the exposed steel and see how it behaves (+ extra shiny!). Natural/forced patina > lacquer. I’d scratch lacquer off the list entirely.
 

Schnabelhund

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I noticed CCK steel is quite reactive. I think mine has something to do with the grind marks - heavily textured from the grinding process, no polish to speak of. My guess it that water/moisture tends to hide in the rough finish, providing a better environment to produce rust than a nicely polished surface.

Personally I don’t mind too much, as I only use it for butchery and the rare occasion something huge needs to be broken down. It’s not so pretty of a knife that I can’t just rub off the rust with some stone mud.

A different angle to your options would be to polish the exposed steel and see how it behaves (+ extra shiny!). Natural/forced patina > lacquer. I’d scratch lacquer off the list entirely.
I see, the grind marks leave the blade with a lot of surface area. Makes sense. I could sand them down and polish the blade like you suggested, or maybe just leave a patina in the "ridges" and keep the rest shiny. I'll forget about the lacquer. Thanks for your help!
 
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Schnabelhund

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Buy the stainless version of it.
Well, I own the carbon version already and love it. I would have chosen a stainless clad carbon CCK in the first place if there were one.

Anyway, I decided to take the patina route, then rub it off close to the edge and keep slicing meat for a week. Who knows, maybe it'll look good enough for the patina thread some day :) Thanks again!
 
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Pie

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Just thinking about this makes me want to mirror polish my 2203. I’ll just add that to my heap of projects I don’t have time for 😁.

Enjoy, and post the after picture too!
 

MowgFace

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Well, I own the carbon version already and love it. I would have chosen a stainless clad carbon CCK in the first place if there were one.

Anyway, I decided to take the patina route, then rub it off close to the edge and keep slicing meat for a week. Who knows, maybe it'll look good enough for the patina thread some day :) Thanks again!

Sounds like you need to peruse @Carl Kotte 's Patina thread:


You might already be good enough ;)
 

Schnabelhund

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Just thinking about this makes me want to mirror polish my 2203. I’ll just add that to my heap of projects I don’t have time for 😁.
2203, nice! Is the kurouchi finish still on? The CCK butcher knives look really cool with the KU, but I'm sure they'd look awesome with a mirror polish too.

Enjoy, and post the after picture too!
Thanks, will do!

Sounds like you need to peruse @Carl Kotte 's Patina thread:


You might already be good enough ;)
Awesome thread :D But I'm afraid my knife doesn't look good enough for either of the patina threads as it looks like new right now. Maybe in a week or two 😁
 
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Schnabelhund

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Hm, I tried to force an instant coffee patina, but I'm pretty bummed by the result. It's very uneven and has hues of orange and yellow. I should have stuck with oxalic acid since it worked pretty much perfectly the first time. I'll give it another try in a couple of days.
 
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Jville

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If you think about Japanese chefs that are using single bevel knives and doing a lot of fish etc. they aren’t going to get the same type of reaction as someone in a western kitchen maybe cutting 50lbs of onions or lots tomatoes etc.
 

Schnabelhund

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If you think about Japanese chefs that are using single bevel knives and doing a lot of fish etc. they aren’t going to get the same type of reaction as someone in a western kitchen maybe cutting 50lbs of onions or lots tomatoes etc.
Fair enough, but I'm only a home cook who mostly cooks Chinese and I still had issues with reactivity, at least with this particular knife. And I imagine pro chefs in Japanese kitchens would have to take good care of their usubas to keep them shiny when prepping similar amounts of scallions, wouldn't they? If there's nothing special about the way they maintain their blades, the only explanation I have at the moment is that they may tend to use higher quality steels.
 
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Fair enough, but I'm only a home cook who mostly cooks Chinese and I still had issues with reactivity, at least with this particular knife. And I imagine pro chefs in Japanese kitchens would have to take good care of their usubas to keep them shiny when prepping similar amounts of scallions, wouldn't they? If there's nothing special about the way they maintain their blades, the only explanation I have at the moment is that they may tend to use higher quality steels.
Whether or not steel patinas is mostly a question of it's alloy content and what you are cutting not the steel's "quality". Scallions do not have the same affect on a blade as say red onions which have a much greater moisture content. If you aren't cutting a lot of reactive foods then you can get away with less patina on a fully reactive knife. It wouldn't work for me because the moisture content and acidity of the ingredients I mainly work with would result in a lot of discoloration, funky smells, and less shelf-stable prepped ingredients. I'm also lazy and don't want to babysit my tools. So I prefer a robust patina on non stainless blades. But I don't usually do anything special to achieve it. Just stick it in the home drawer and ask my wife to use it for a few weeks. She is a master patinater.
 

spaceconvoy

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Fair enough, but I'm only a home cook who mostly cooks Chinese and I still had issues with reactivity, at least with this particular knife. And I imagine pro chefs in Japanese kitchens would have to take good care of their usubas to keep them shiny when prepping similar amounts of scallions, wouldn't they? If there's nothing special about the way they maintain their blades, the only explanation I have at the moment is that they may tend to use higher quality steels.
They use baking soda to scrub off the patina after every shift, traditionally with the top of a diakon radish. I tried that method for a while but I could never get my knives super clean looking. It's probably a combination of cutting low-acidic foods, carbon steel with fewer impurities, and scrubbing it every day using more elbow grease than your average home user is willing to put in that makes it work for them. Still, even if you're lazy about it it's a nice way to tame the patina so it's nice and stable but more muted.
 

Schnabelhund

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If you aren't cutting a lot of reactive foods then you can get away with less patina on a fully reactive knife. It wouldn't work for me because the moisture content and acidity of the ingredients I mainly work with would result in a lot of discoloration, funky smells, and less shelf-stable prepped ingredients. I'm also lazy and don't want to babysit my tools. So I prefer a robust patina on non stainless blades. But I don't usually do anything special to achieve it. Just stick it in the home drawer and ask my wife to use it for a few weeks. She is a master patinater.
They use baking soda to scrub off the patina after every shift, traditionally with the top of a diakon radish. I tried that method for a while but I could never get my knives super clean looking. It's probably a combination of cutting low-acidic foods, carbon steel with fewer impurities, and scrubbing it every day using more elbow grease than your average home user is willing to put in that makes it work for them. Still, even if you're lazy about it it's a nice way to tame the patina so it's nice and stable but more muted.
I see, looks like I'll have to accept either hard work or (at least a light) patina. I'll try the baking soda way for some time and see how that goes.
 

natto

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A damp and a wet towel can help to keep the steel shiny. Wiping the knife clean and dry, putting down to a dry spot only. Best to do this every time the knife is put down. And wipe it repeated with longer sessions.

zen works :)
 

Schnabelhund

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A damp and a wet towel can help to keep the steel shiny. Wiping the knife clean and dry, putting down to a dry spot only. Best to do this every time the knife is put down. And wipe it repeated with longer sessions.

zen works :)
Neat, I think I'll also put a pinch of baking soda into the water I wet the towel with, thus combining your suggestion with @spaceconvoy's. I'm sure it won't hurt, will it?
 
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