About carbon steel

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ocho

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Hi, been reading the posts but still don't get and Idea:
I know there are several types of steel: withe 1, withe 2, blue 1 and blue2, sweeden, and the list goes on and on.
My question is : is any one less reactive with onions? I'm thinking on getting a Nakiri, a project knife with crapy finishing and handle, but a good quality blade. Any suggestion?
And: what type is the one on Carbonext ( I have one , just curious).
 
I can only speak of AISI W1 and W2 (NOT white 1 and white 2!!). In my experience they seem to only be moderately reactive for a very short time (until the patina builds up)...but you'll probably have a tough time finding a nakiri in those steels, unless you go with a custom maker.

I know that doesn't help a lot...but its all I've got :)
 
In my experience, it depends on the heat treat, the same steel can be more or less reactive. In general, steels with more alloying elements and/or higher purity can be less reactive.
You shouldn't really need to worry about the reactivity though if you just wipe the blade while working, though different types of cladding material can be quite reactive.
 
Carbonext is a semi stainless blade.
 
In my experience White is more reactive than Blue, but if you're looking for a carbon/stainless laminate, it shouldn't be too much of an issue since the exposed reactive steel is only along the edge.
 
I wanted to add something similar to cheezit's comment.
Most Japanese makers do san-mai construction, aka laminated. The type of cladding (outer layer) will determinate how reactive the knife is. Obviously, the exposed core steel will be subject of oxidation as well, but that's a smaller portion of the knife.
My understanding is that the more pure the steel is - more reactive it is. So white #1 > white #2 > Blues being less reactive.
 
My understanding is that the more pure the steel is - more reactive it is. So white #1 > white #2 > Blues being less reactive.
First of all, what do you mean by "more pure"? Higher percentage of carbon? Lack of other elements?

Second, in my experience, what you wrote is NOT true. I have several less expensive carbon steel knives (including two that are likely made of white #3 which is a lower quality steel) and they are WAY more reactive than my white #2 and white #1 steel knives.

The reactivity of my carbon steel knives is directly related to how inexpensive they are - the cheaper they are, the more reactive they are.
 
In my experience the reactiveness of the core steel in no problem for us home users - not in terms of causing damage to the blade anyway. As long as you wipe the blade once in a while (as in after you´ve finished cutting each engredient) it even takes a while to form a patina. I like to touch up the edge on high grit stones and strop fairly often, and that might be part of the reason - but the core steel on my knife with
white #2 hasn´t even got a patina on the core steel after three months of daily use :)
On the other hand I have a honesuki in AS steel. I´ve only used it for breaking down chicken and it developed some patina on the core steel after just a couple of hours of use.
I don´t think you should be "afraid" of the reactiveness of carbon steel. If you don´t leave it dirty or wet for a longer period of time, the only thing that can happen is a change of color. At least as far as I know.
- Kim
 
First of all, what do you mean by "more pure"? Higher percentage of carbon? Lack of other elements?

In my understating more pure carbon steel has less elements added to it.
White 3 is very similar to White 1 but little bit less carbon. I have to doubt that there is any real dependency on $$$ vs How reactive the knife is.
In addition we are talking about steel, not particular knives in this thread I think ;)
 
52100 is the least reactive of the carbon steels. After that you would need to move up to a semi stainless.

Hoss
 
I may be mistaken, but I think the OP is more concerned with oxidizing the vegetables being cut, and not the steel? Cutting onions with a KU knife leaves an unappealing pile of brown mush...
 
In my understating more pure carbon steel has less elements added to it.
White 3 is very similar to White 1 but little bit less carbon. I have to doubt that there is any real dependency on $$$ vs How reactive the knife is.

Then, how about naming some examples that you can refer us to?

In addition we are talking about steel, not particular knives in this thread I think ;)

I was using my knives as examples of the steel. Or do you expect members here to be buying bars of steel and testing them for reactivity?

And, you're the one who wrote this: So white #1 > white #2 > Blues being less reactive. By this diagram, white #2 would be ">" than white #3, but now, apparently after you looked up the composition, you're taking the position that it doesn't fall into this diagram?

How about getting it right first before posting?
 
I may be mistaken, but I think the OP is more concerned with oxidizing the vegetables being cut, and not the steel? Cutting onions with a KU knife leaves an unappealing pile of brown mush...

No. You're right. But Ruso's statement isn't correct based on my experience. Perhaps Ruso can identify those examples that support his broad generalization.

In fact, I used a Carter SFGZ Funayuki White #1 for well over a year, sharpened a few times, and used it nearly daily for months. It was even left out without having been cleaned or wiped down for a significant amount of time (several hours) after being used and the core steel showed very little sign of browning. The edge area certainly developed a patina, but it was rather unreactive compared to other carbon steel knives that I've used, including white #2 and white #3 knives.

My recommendation is that, if the OP is interested in buying a carbon steel knife, read up on the makers of the knives that he/she is interested in, find out how reactive that maker's knives are, and go from there. A generalization like white#1 is more reactive than white#2 is misleading.
 
The general "wisdom"* suggests that the higher the amounts of sulfur and phosphorus, the more "reactive" the steel. In the case of the Hitachi steels, that would mean White < Yellow < SK-x

With my chemist's hat on, I doubt very much that it is as simple as this.


* suggested many times in the past, e.g. in the case of the Fujiwara FK-H (SK-4, very reactive (allegedly))
 
But wouldn't it be the core of the knife causing the reactivity? Seems to me the KU finish shouldn't be very reactive.

Soft iron cladding is generally far more reactive than hagane. Kurouchi can attenuate reactivity, but not always. In my hands a Moritaka KU (after the lacquer had worn off) was ridiculously, almost rust-on-sight reactive. Nothing could be done with it.
 
In my experience, the factors that matter most with respect to reactivity of carbon steels (close to zero chromium in solution) are: purity of the steel (S n P), surface area, and finish. Purer steel, less exposed carbon steel (and/or iron cladding), and finer polish will all reduce the rate of reaction significantly. As for patina, on a lot of knives, patina can nearly eliminate the reactivity. On some of the cheaper knives (SK4, etc) the patina often dissolves right into certain foods. It's disgusting.
 
And, you're the one who wrote this: So white #1 > white #2 > Blues being less reactive. By this diagram, white #2 would be ">" than white #3

I beg your pardon but where did you find White #3 in my example? Your brought it up from nowhere in your answer to my post. I actually forgot that White #3 exists, I have not seen a knife made out of it so it's kinda became non existent in my mind :(
 
But wouldn't it be the core of the knife causing the reactivity? Seems to me the KU finish shouldn't be very reactive.

The reactivity will depend on the composition of the mild steel used, but Gokunan-tetsu, which is commonly used for KU knives, tends to be very reactive, especially with cabbage, onions, mangos, etc.
 
I may be mistaken, but I think the OP is more concerned with oxidizing the vegetables being cut, and not the steel? Cutting onions with a KU knife leaves an unappealing pile of brown mush...

Hi, first: sorry for my late response and thank you all for your input.
Chezzit nailed my concern, reading past posts some how got the idea that some carbon steel knives make the onions black patina or not
 
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