# Blue patina



## TaJ (Jan 20, 2014)

On the weekend i used the Singatirin Gyuto for the first time. I was all like, hey, let's go slow and just cut some meat, not some acidic vegetables at first. So, i prepared a nice big duck breast and started to cut it in thin slices. Almost as soon as i started slicing the blade started reacting and discoloring blue.
:eek2:

I looked around and found this thread:
http://www.kitchenknifeforums.com/showthread.php/2363-Should-I-force-a-patina-on-new-knife/page3
The patina looks like in the pictures on that page. Right now, i'm not sure if i like the looks. Some like such patina, to me it looks just like stained metal, still. Maybe it will grow on me though. I rinsed the blade under _very_ hot water after cooking. What started to build up while rinsing was small reddish dots (rust i guess), which i was almost completely able to remove with a green sponge. An interesting (to me) observation, when i apply Camellia oil, the patina is still visible, but fainter and the color is gone. It just looks darker than the rest of the blade. The color is back to blue once i wash off the oil with soap.

Is it possible to completely remove the patina again? Since it's not added material but the steel which reacted chemically i can think only of abrasives, but i'm asking still to be sure. I've read about a video from Jon about keeping a blade patina-free (for knives used for sushi?) but i've seen no link and could not find it.

Another question, the meat juices produced the patina but of course only on the spots the meat touched the blade. Did anyone cook medium rare meat and then tried to cut it and rub it on the whole blade surface, to have the blue patina develop all over the blade? How did that work out?

Cheers!


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## bkultra (Jan 20, 2014)

You can remove patina with a product called Flitz. There are a few ways but I find this the fastest and easiest way. Bar keepers friend also works.


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## tripleq (Jan 20, 2014)

Your can certainly produce a patina over the entire blade as you mention above. You can leave warm blood on the blade as well. There are a lot of things that will produce patina such as not vinegar among others. Any abrasive will remove the patina. The rougher the abrasive the more scratches it will put on your surface. I find fritz or simichrome polish do a fine job without scratching the surface. A good scrubbing with a scotch brite pad often works just as well depending on the patina.


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## Jim (Jan 21, 2014)

Don't open this thread! :viking:


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## stereo.pete (Jan 21, 2014)

Embrace the blue flames of patina caused by warm animal blood for the beauty that it is!


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## greasedbullet (Jan 21, 2014)

just think of it as your own personal light saber.


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## Ruso (Jan 21, 2014)

Bar Keepers Friend work wonder when removing pating from the blade. Unfortunately you will have to do a touch up on the stone as most likely the process will dull the knife a little bit.


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## toddnmd (Jan 21, 2014)

stereo.pete said:


> Embrace the blue flames of patina caused by warm animal blood for the beauty that it is!



Amen to that!


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## EdipisReks (Jan 21, 2014)

maybe we should have a new rule: if metal reaction is going to freak you out, don't buy a carbon steel knife.


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## Benuser (Jan 21, 2014)

You may reduce the steel's reactivity by applying a baking soda solution.


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## EdipisReks (Jan 21, 2014)

Benuser said:


> You may reduce the steel's reactivity by applying a baking soda solution.



Hot vinegar bath works well too.


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## TaJ (Jan 21, 2014)

Thanks for all the info. I'm not so keen on using abrasives and might just let the patina develop on its own or use my next duck breast to paint it blue.

I've read that Japanese chefs keep the blades (almost?) patina free. Also, in online videos of Japanese chefs i see clean deba and yanagiba. How do they go about that? Are they using abrasive products on a daily basis? O do they use the baking soda solution or vinegar? If that reduces the steel's reactivity then this is worth a try, maybe for the fish-knives.


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## bkultra (Jan 21, 2014)

Japanese chefs clean their knives after every shift. Normally with powered cleanser and apply it with a daikon radish


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## TaJ (Jan 21, 2014)

bkultra said:


> Japanese chefs clean their knives after every shift. Normally with powered cleanser and apply it with a daikon radish



That sounds like abrasive powder, maybe very fine. Might it be that in the radish there is some agent which helps cleanign? Interesting.


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## Notaskinnychef (Jan 21, 2014)

I love patina, personally i will never remove mine, but to each their own


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## Geo87 (Jan 21, 2014)

Any kind of metal polish will do... Mag wheel polish... Whatever. You can get metal polish from most hardware stores . 

I only ever remove patina for the fun of putting it back on again! 

The warm blood patina so far is the best for me as I love blues 
You could polish it off and try again but smear the blood over the whole blade and leave for 5 mins or so.


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## TaJ (Jan 21, 2014)

Geo87 said:


> Any kind of metal polish will do... Mag wheel polish... Whatever. You can get metal polish from most hardware stores .
> 
> I only ever remove patina for the fun of putting it back on again!
> 
> ...



I think that's what i'm going to try. Getting the finest grit kind of polish and remove the patina. Then fixing duck breast again and paint the knife with the juices.


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## kpnv (Jan 21, 2014)

japanese chefs use baking soda to clean their knives at the end of a shift. the radish, usually the ends or peel is used as a scrubber just because it's there and it's gentle. after it's cleaned down, they'll sharpen and polish. because they spend so much time polishing and maintaining, they'll probably never use hard abrasives as that stuff will ruin the finish and in the case of sushi/sashimi, affect the quality of the raw fish. sharpening will also remove patina, obviously.

another important thing to note is they'll also have 2 towels out when cutting stuff. one is damp and laid next to the cutting board. this is used to wipe the knife down between cuts and keep food off the knife. the towel gets rinsed out under hot running water every now and then. the other towel is bone dry and used to dry the knife after cutting jobs.

if you want to attempt to keep your carbon patina free, you'd need a similar regimen at the very least. if you're cutting meat or very acidic foods, consider using a stainless instead and use your carbons for low acid stuff or fish and white meat.


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## TaJ (Jan 21, 2014)

Ah i see. So, i'll try to do it this way (baking soda) when i use my Deba and Yanagiba the first time. If i can't remove the patina this way i'll use the polish. When you say they sharpen and polish, you mean polishing the edge, right? For preparing fish i think i can manage that kind of care and the other knives will be subject to experimenting with patina.


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## bkultra (Jan 21, 2014)

TaJ said:


> That sounds like abrasive powder, maybe very fine. Might it be that in the radish there is some agent which helps cleanign? Interesting.



The radish could be replaced with something like a wine cork... The radish is just something they always have on hand and it works.


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## GlassEye (Jan 22, 2014)

Fine sharpening stone mud works well for removing patina, just gently use a cork to polish with the mud in the direction of the grind marks. I have found the mud to cause no scratching, unlike Bar Keepers Friend or similar cleaners which might cause light scratching. Continual cleaning of the staining like this will make the blade less reactive over time.


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## erikz (Jan 22, 2014)

My Takeda Honesuki also got a (in my opinion) really nice blue patina. Seems that poultry is doing the trick for me on Aogami Super.

I'd also suggest to apply some ss mud to see if it helps to remove the patina.


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## Keith Sinclair (Jan 22, 2014)

Yanagi's cutting only sashimi & sushi topping do not react that much at all.Pretty easy to keep them cleaned up.Gyuto's however cutting everthing will patina quickly.Personally on Gyuto's,petty etc.let the patina go,protects fr. rust as long as used alot.


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## TaJ (Jan 22, 2014)

Good tips. I've read up a bit more on baking soda being Sodium bicarbonate (NaHCO3) and being alkaline. Someone wrote that it passivates steel somehow. Maybe it's reacting with steel/iron and builds a kind of invisible 'patina' which obstructs the acid based patinas or rust from developing? Just a wild guess, i did not find confirmation of that thought yet.


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## Benuser (Jan 22, 2014)

http://www.kitchenknifeforums.com/showthread.php/2749-Passivation-of-Carbon-Knives


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## panda (Jan 22, 2014)

i've tried nearly everything, and scrubbing with baking soda has been the best result for me, as far as reducing reactivity.

i tried reading that thread but it gave me a headache, i don't care about the why, only the how, lol.


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