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Will kono blue #2 steel rust and react?

Sat Apr 06, 2013 8:14 am

Dear Mark,
I am very interested in buying a Fujijama Gyuto blue #2, but I am concerned about rusting and reacting with acid. Could you be so kind, and tell me if this knives are made with standard blue steel that will rust and react or they have something added to them that makes them more resistant?

Thanks in advance,

Re: Will kono blue #2 steel rust and react?

Sat Apr 06, 2013 8:30 am

It will react and Patina like any other carbon steel. Blue steels generally are less reactive than White steels, but they still will rust if left wet or in a damp environment and will react to acidic foods. A good patina will reduce the reactivity though.

Re: Will kono blue #2 steel rust and react?

Sat Apr 06, 2013 9:01 am

Yes Tim is correct. :)

Re: Will kono blue #2 steel rust and react?

Sat Apr 06, 2013 10:47 am

All of the popular carbon alloys are reactive. Some are more reactive than others, some less. With 0.50% chromium, all of the Aogami steels are on the "less" side of the Shirogami/Shiro-ko steels which have none. But there are certainly other carbons less prone to stain and rust.

The first thing to know about carbon is that it really doesn't require much more care than stainless or semi-stainless, but it requires it NOW. The second thing to know is that it does require some extra care.

There are a couple of ways to get ahead of the stan/rust problem. A patina is one of them. You can force a patina, allow one to develop naturally, or use something in between -- for instance, by scouring the knife with BKF and not neutralizing it.

A patina isn't perfect protection. Even after you've got a good one, you have to baby it (no scouring), while keeping an eye on the knife to make sure nothing negative is happening. And every once in a while, it's a good idea to scour it off completely to take a good look at the knife; and then start a new one.

There are some very interesting and attractive forced patinas. Google "mustard patina" and see what you see.

It's only a matter of style, but I prefer to clean my knives with baking soda and a green Scotch-Brite scouring pad. In the bad old days we used to use corks to rub the baking soda in or even potatoes, but those were the bad old days. Scotch-Brite is your friend.

Baking soda stabilizes the alloy to some extent and makes it less reactive -- for a little while. The most important thing is that it does a great job of scouring stains off the knife, while neutralizing anything harmful stuck in the alloys (microscopically small) pits. A baking soda finish isn't "bright as new," but the dull-grey gleam that you see with well used and well-maintained tools. If you rinse and wipe your knives immediately after cutting something reactive, and never leave your knives laying around after prep without a final, rinse and wipe, and if you allow them to completely dry before putting them away, you won't have to do the baking soda very often. If you're human, you'll do it more frequently, as you spot spots.


Re: Will kono blue #2 steel rust and react?

Sat Apr 06, 2013 7:46 pm

I fold up a towel or something beside the cutting board and wipe the knife between cutting tasks; helps to reduce the in-between staining. Then after I'm done I give it a wash, etc. Not a big fan of patina; I like to keep the knives looking shiny.

I purchased a Nakiri off Ebay that was apparently made 30 years ago in Sakai, but have no idea what kind of steel it is...
but I really like the height and the profile of it. It's a great knife...gets very sharp, cuts well and holds a nice edge.
Easy to sharpen on the Coticule.

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