high carbon steel for food

[ken1111]

I notice some bare 1095 steel blades i use for fruit leaves a bit of patina on the food. So much to a point i can taste it in my food. I have tried gun blue and ketchup and mustard patina. Is there a 'stronger' patina that will not come off in food? I know when i leave the natural forge finish that does not come off in food. Though re heat treating a blade with epoxied handles is not a good option.

Perhaps boiling vinegar? Ora certain type of acid wash? Ne 1 have experiencein this?

 

[Obsessed with Edges]

Anything acidic in food will continuously react with the steel, even if some patina is already in place. The reaction is always going to impart some changes in taste or odor. it'll be stronger on 'clean' steel where no patina has yet formed. If the taste/odor is enough of a problem, using a stainless blade is the most sure-fire way to eliminate that. With some high-carbon steels, the taste or odor might diminish a little bit over time and with repeated exposure, but it'll still always be there to some degree. It basically comes down to a decision, if you are willing to tolerate the 'character' of the steel in the taste of your food, or not. If not, then using a stainless blade for food prep is probably the best solution.


David

 

[BluntCut MetalWorks]

one of my super thick & pretty patina progression: green mango -> beef blood -> 3x boiled distilled vinegar (scrub between boil). Worked pretty well for 1095 & 52100 & some unknown carbon(s).

however newly exposed sharpened edge/bevel gonna stink a little.

 

[ken1111]

Anything acidic in food will continuously react with the steel, even if some patina is already in place. The reaction is always going to impart some changes in taste or odor. it'll be stronger on 'clean' steel where no patina has yet formed. If the taste/odor is enough of a problem, using a stainless blade is the most sure-fire way to eliminate that. With some high-carbon steels, the taste or odor might diminish a little bit over time and with repeated exposure, but it'll still always be there to some degree. It basically comes down to a decision, if you are willing to tolerate the 'character' of the steel in the taste of your food, or not. If not, then using a stainless blade for food prep is probably the best solution.


David

I get that however i was wondering if you could develop a more stable patina that would lessen the effect when cutting into normal food. I gave a forge finish for example which does not do this. However i get to much warping and cracking if i heat treat with the final primary grind on it.

 

[ken1111]

one of my super thick & pretty patina progression: green mango -> beef blood -> 3x boiled distilled vinegar (scrub between boil). Worked pretty well for 1095 & 52100 & some unknown carbon(s).

however newly exposed sharpened edge/bevel gonna stink a little.

I think i am fine with the stink but does it leave residue on your food? lol i may change my mind on the stink after the blood tho lol.

 

[Obsessed with Edges]

In a sense, the 'stink' or 'taste' of the acid & carbon steel reaction IS the residue. The reaction creates an exchange of ions between the food acids and the iron in the steel, and that alters the physical properties (taste/smell/color) of both. You might notice with some foods, like fruits, there'll be some blue/purple/black color transfer from the steel to the food, which is the black iron oxide created in the reaction. Not harmful to ingest, but not so pretty either.

I think (though I'm not sure), the 'forge finish' is basically a layer of carbon scale left on the blade(?). If so, the coated effect may help minimize direct contact between the steel and the acids in the food. Seems like an extreme measure though, if altering or damaging the heat treat is a (possible) side-effect. I'd think the trade-off wouldn't be worth it, personally. A true 'patina' of any kind is always going to be very shallow, just a few molecules thick most likely, so there'll always be some likelihood of acids interacting with the steel underneath that thin layer. To some degree, the same acids that create the patina also work to dissolve it a little (therefore exposing 'clean' steel underneath), which is why the patina constantly changes over time, with repeated exposures.

I'm sure harsher acids would work deeper, but they'd also be a greater risk for creating more corrosion issues as well, if not thoroughly cleaned up & neutralized.


David

 

[ken1111]

In a sense, the 'stink' or 'taste' of the acid & carbon steel reaction IS the residue. The reaction creates an exchange of ions between the food acids and the iron in the steel, and that alters the physical properties (taste/smell/color) of both. You might notice with some foods, like fruits, there'll be some blue/purple/black color transfer from the steel to the food, which is the black iron oxide created in the reaction. Not harmful to ingest, but not so pretty either.

I think (though I'm not sure), the 'forge finish' is basically a layer of carbon scale left on the blade(?). If so, the coated effect may help minimize direct contact between the steel and the acids in the food. Seems like an extreme measure though, if altering or damaging the heat treat is a (possible) side-effect. I'd think the trade-off wouldn't be worth it, personally. A true 'patina' of any kind is always going to be very shallow, just a few molecules thick most likely, so there'll always be some likelihood of acids interacting with the steel underneath that thin layer. To some degree, the same acids that create the patina also work to dissolve it a little (therefore exposing 'clean' steel underneath), which is why the patina constantly changes over time, with repeated exposures.

I'm sure harsher acids would work deeper, but they'd also be a greater risk for creating more corrosion issues as well, if not thoroughly cleaned up & neutralized.


David

hmm then is there any deposition method to add carbon or some other more inert layer between the steel and food? (besides buying a expensive duracoat or something along those lines) any thing commonly used?

 

[Obsessed with Edges]

hmm then is there any deposition method to add carbon or some other more inert layer between the steel and food? (besides buying a expensive duracoat or something along those lines) any thing commonly used?

It seems like a non-reactive blade coating is the only thing that'd even come close. But, with an edge that gets used, and therefore re-sharpened periodically, it'll be impossible to cover all the bare steel. The clean, un-oxidized steel on the freshly-sharpened bevel will always be interacting (chemically) with anything it touches.

I think most who use a non-stainless blade for food prep, probably have reached some level of tolerance/acceptance for the slight change in taste/smell. I suppose some might even come to a point that they don't conciously notice it anymore. But it takes some time to figure that out, if it's gonna happen. I know in my own experience, I'm always immediately aware of the 'steel' taste in the food I slice with a non-stainless blade. I'm sure I could tolerate it if I had to, but being aware of it always makes me reach for a stainless blade instead.


David

 

[Jason B.]

The problem is the patina.

Clean/remove patina exposing bare steel.

Hand polish blade with rag and fine polish. Just enough to shine the surface, not trying to mirror polish here.

Keep blade clean and when a natural patina starts to develop break out the rag, polish, and get to work.

 

[Obsessed with Edges]

A high polish does help to slow the reaction (reduces surface area exposed), so that could help somewhat. More so to lighten the patina, but there'll still be bare steel exposed. I have a 'carbone' Opinel, pictured below, on which I polished the blade, and it doesn't darken near as fast. BUT, the taste/odor issues are still noticeable with acidic foods, fruits especially. I tested the edge on this knife with grapes, the inside of which immediately turned dark blue when sliced. It's polished steel, but still bare carbon steel nevertheless. The reaction will still be there.


David

 

[Bill DeShivs]

Gold plating the blade would stop it.

 

[ken1111]

It seems like a non-reactive blade coating is the only thing that'd even come close. But, with an edge that gets used, and therefore re-sharpened periodically, it'll be impossible to cover all the bare steel. The clean, un-oxidized steel on the freshly-sharpened bevel will always be interacting (chemically) with anything it touches.

I think most who use a non-stainless blade for food prep, probably have reached some level of tolerance/acceptance for the slight change in taste/smell. I suppose some might even come to a point that they don't conciously notice it anymore. But it takes some time to figure that out, if it's gonna happen. I know in my own experience, I'm always immediately aware of the 'steel' taste in the food I slice with a non-stainless blade. I'm sure I could tolerate it if I had to, but being aware of it always makes me reach for a stainless blade instead.


David

i see the problem is i want to use the knives i make in food prep however i am unable to do a ht on a stainless steel at the moment. =( well maybe in the future

 

[ken1111]

The problem is the patina.

Clean/remove patina exposing bare steel.

Hand polish blade with rag and fine polish. Just enough to shine the surface, not trying to mirror polish here.

Keep blade clean and when a natural patina starts to develop break out the rag, polish, and get to work.

I totally agree with this just thought there might be a way to make a more "stable" patina. The taste of steel is considerably less when there is no patina on it. the problem is that the next time i use it there is a patina there lol and like you said i would have to clean it off.

 

[ken1111]

The problem is the patina.

Clean/remove patina exposing bare steel.

Hand polish blade with rag and fine polish. Just enough to shine the surface, not trying to mirror polish here.

Keep blade clean and when a natural patina starts to develop break out the rag, polish, and get to work.

I totally agree with this just thought there might be a way to make a more "stable" patina. The taste of steel is considerably less when there is no patina on it. the problem is that the next time i use it there is a patina there lol and like you said i would have to clean it off.

 

[Obsessed with Edges]

i see the problem is i want to use the knives i make in food prep however i am unable to do a ht on a stainless steel at the moment. =( well maybe in the future

I've always been somewhat curious as to the effects of gradually increasing chromium content, vs. the perception of flavor/smell created by acid interaction in carbon blades. A true 'stainless' blade typically has ~12% chromium or more. I wonder if there's a simpler carbon steel, not nearly stainless, but with a slightly higher chromium content than something like 1095 (has none whatsoever), which might provide a high-enough threshold to minimize that perceptible alteration in taste, when cutting foods. Would be an interesting experiment, for someone with the means to do it.


David

 

[Bill DeShivs]

D 2 might work.

 

[ken1111]

D 2 might work.

i may try D-2for the batch of blades. The 20 min soak time i think would be hard to hit in my finicky charcoal furnace with out going over. I just ground out an O-1 blade but i dun hold high hopes.... it is only a measly .55% compared to the 12% D2 has.

 

[Bigfattyt]

One trick, that seems to do some good, is running the blade under water and cutting the food with a wet blade.

I saw a video at a Japanese fish market, where they were butchering giant tuna. The guy using the tuna sword kept wiping it down, and then running it under water before the cut. (if I am remembering correctly).

I do this with one of my 1075 blades, and on 1095. It does seem to help. I also have a boiled vinegar patina on my high carbon blades. Nothing is perfect for keeping a bit if tang out of the fruit, but it does seem to help.

I mean shoot, gourmet chefs have been using high carbon blades for as long as there have been gourmet chefs. Seems like universal stainless steel knives are a modern invention.

I only have two knives with D2, but it is for sure less reactive with the food.

 

[SweptEdge]

I was just going to post a similar question, but I saw this thread, and I wanted to ask if people have tried using a Tuf-Cloth on their carbon blades, and if so, what were the out comes? Did the patina come later on, after the Tuf-Cloth wore off. Maybe its more of a issue of not ingesting the Tuf-Cloth chemicals.

 

[Obsessed with Edges]

I sort of view D2 as very nearly stainless anyway, just a percentage point or so of chromium (maybe 1/2 a percent) away from the technical definition of 'stainless'. My earlier ponderings were directed more at steels that might be in the middle ground, maybe higher than 1-2% chromium, and less than 10%. It would be interesting to see where the character of the steel might start to swing away from the food-reactive and/or flavor-altering behavior of 1095 and similar steels. I seem to recall seeing some spec'd in the 4-5% range of chromium, but I don't remember what they were.


David