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lanel
07-16-2013, 09:58 AM
I have a 240 tanaka blue #2 gyuto and I'm not certain what is happening. When cutting most anything it gets a yellowish/orange color on it, which can be wiped off with a side towel. My question is, is this patina, or is it something else I should worry about? Compared to my masamoto virgin carbon this knife seems super reactive. Any thoughts or insight would be appreciated.

bkultra
07-16-2013, 10:12 AM
It's not uncommon to have a reaction when using carbon steel. Here is a great video about how to properly use a carbon knife. As the knife builds a patina it will lessen the reaction (assuming you are letting a patina form).


http://m.youtube.com/watch?v=tza5pymb5yg

Timthebeaver
07-16-2013, 10:13 AM
I have a 240 tanaka blue #2 gyuto and I'm not certain what is happening. When cutting most anything it gets a yellowish/orange color on it, which can be wiped off with a side towel. My question is, is this patina, or is it something else I should worry about? Compared to my masamoto virgin carbon this knife seems super reactive. Any thoughts or insight would be appreciated.

The Masamoto VC is a single piece of high-carbon steel, the Tanaka has a high-carbon (Blue #2) core with soft iron "damascus" cladding. The soft iron is far more reactive than the hagane. Reactivity should decrease with use as a patina builds. You could force a patina with mustard/vinegar/acid/etc. if you wished.

lanel
07-16-2013, 10:27 AM
Thanks for the quick responses, I'm aware of patina and how it forms. I think I was a bit vague in the op. my masamoto has patina that is grey black. What I wondered is if the orange is just the color I can expect from this knife and its ok to leave it on? Or is this a bad thing and I'm going to want to remove this. Thanks again for the info.

Timthebeaver
07-16-2013, 10:33 AM
There is information on Tanaka blue #2 & patina in this thread.

http://www.kitchenknifeforums.com/showthread.php/12968-tanaka-blue-2-love

NO ChoP!
07-16-2013, 10:56 AM
My experience is soft iron cladding is a pita, and the Tanaka is no exception. An acid or vinegar etch is probably a must.

GlassEye
07-16-2013, 12:53 PM
My Tanaka knives were the same when I got them, but after giving them a full natural stone polish it has become a non-issue.

panda
07-16-2013, 08:48 PM
I highly recommend acid or vinegar patina on Tanaka blue, its very reactive until then. After it hardly shows.

Drum N Baste
07-16-2013, 09:53 PM
Orange is not patina and patina doesn't wipe off with a side towel. Orange is bad.

greasedbullet
07-16-2013, 10:09 PM
I agree with the general consensus so far, acid or vinegar etching is the way to go. Here is a tutorial (http://www.kitchenknifeforums.com/showthread.php/6474-Damascus-Knives-amp-Re-Etchng) by Dave Martel for acid etching. I just did this and it is AMAZING. Also here (http://www.kitchenknifeforums.com/showthread.php/7255-Hot-Vinegar-Patina/page6) is a thread about hot vinegar etching, but it looks like it doesn't turn out too well on Tanakas, but the guy could have been doing it wrong, in that particular instance.

greasedbullet
07-16-2013, 10:31 PM
Also here (http://www.kitchenknifeforums.com/showthread.php/7255-Hot-Vinegar-Patina/page6) is a thread about hot vinegar etching, but it looks like it doesn't turn out too well on Tanakas, but the guy could have been doing it wrong, in that particular instance.

It looks like he was doing it wrong. Apparently if you do two 5 minute long baths in the hot vinegar then it turns out a lot better. But I personally have not done this.

augerpro
07-16-2013, 11:14 PM
Orange is not patina and patina doesn't wipe off with a side towel. Orange is bad.

How bad? I have a Shig and recently went down this road of dealing with reactivity (started a thread here) and ended up with something I *think* I can live with. But I do still get some orange-ish staining. Only from garlic and it is quick. I just wash the blade with soap and water (some staining still remains) and haven't thought to much about it. Should I worry?

BTW I'm interested in the comment about polishing reducing the reactivity. What would be a good grit? Or for the matter, what is a good finishing technique in general for surface to get low stiction? One thing I noticed when I did the vinegar bath on my Shig is that it stuck like a mother* afterwards. Had to use 00 then 0000 steel wool and it is pretty good now, though I'm not sure if it is as good as when I bought it since I didn't have much time on it before I tried the vinegar.

I think the main change that makes my Shig livable is having a damp rag next to the board and wiping it every time I set the knife down.

Drum N Baste
07-16-2013, 11:36 PM
You're still getting some orange and some staining because the iron hasn't fully passivated. Scrub your knife down every time you use it with some BKF, and after a few days you'll be fine.

augerpro
07-17-2013, 01:53 AM
I guess I was under the impression BKF would remove the patina?

franzb69
07-17-2013, 02:50 AM
I guess I was under the impression BKF would remove the patina?

it definitely would.

and leave a nice polish.

Drum N Baste
07-17-2013, 06:57 AM
I guess I was under the impression BKF would remove the patina?

On the contrary, it will actually help create a patina.

franzb69
07-17-2013, 07:16 AM
On the contrary, it will actually help create a patina.

if you rinse it and rub it with baking soda, it stops patina from forming.

=D

forgot to mention that sorry.