# patina development with various foods



## Keith Neal (Apr 7, 2012)

It might be of interest to put together a list of foods that create patina more than others. If you will tell me what foods have what degree of reactivity in developing patina, I will compile a list and update it as data is provided.

Perhaps a scale of zero (none) to five (most) would help express the degree to which various foods develop patina. For instance:

FOOD DEGREE comments
blood 5 blue patina
mustard 4 brown patina
citrus fruit 4 brown patina
collard greens 0 

If there is interest in this, please provide your input.


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## dav (Apr 7, 2012)

As a newbie was going to ask this same question Keith! I have a few nice new polished knifes and was wondering how I could develop a "nice" patina - not knowing how or what foods do what. Looks like I'll be eating and prepping more meat (normally eat mostly fish) as I like the knives I've seen with blue patina's thanks!

I've used my knives (all high carbon steel/reactive) a little and was conscious not to leave them wet for any length of time not wanting rusting etc... but to force a patina what is the best approach say if cutting meat should they be left for a short while or is it enough to wash them fairly quickly allowing the patina to develop over time?


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## oivind_dahle (Apr 7, 2012)

Woulnt patina also depend on:
Type of steel
Time
Temprature
Air/huminity 

?


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## Keith Neal (Apr 7, 2012)

oivind_dahle said:


> Woulnt patina also depend on:
> Type of steel
> Time
> Temprature
> ...



Yes, the degree and maybe color of patina woulld vary with those factors, but I think the relative ranking of various foods would remain fairly constant.


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## Benuser (Apr 7, 2012)

oivind_dahle said:


> Woulnt patina also depend on:
> Type of steel
> Time
> Temprature
> ...



Finish?


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## Pachowder (Apr 7, 2012)

As a newbie as well, it would be great to know. I have so many questions about this but will save for another time


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## stevenStefano (Apr 7, 2012)

Personally I feel that the affect of different foods on patina is highly exaggerated. I personally think it is more to do with the time you have used the knife rather than what foods you cut. I think after a while your knife will form pretty much the same patina no matter what you cut, the knife needs "broken in" so to speak where after a while the reactivity balances out and the patina forms very quickly no matter what you cut


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## tk59 (Apr 7, 2012)

The other day, I used a newly finished petty made from DT-carbon to core strawberries and take apart some chickens. The tip is gray/black from the strawberries. The rest of the knife is blue.


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## stevenStefano (Apr 7, 2012)

My knives go an electric blue colour after a while now when I cut lettuce. Could be that I cut so many different things that the patina changes a lot I guess


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## 99Limited (Apr 7, 2012)

It seems that acidic items turn carbon knives shades of black and proteins turn them blue. What I'm wondering as far as proteins go, does fish have the same effect as beef and what effect does raw versus cooked make. Would you get the same colorization from cutting proteins that were hot from being cooked as you would from cutting proteins that were cooked, but had been thoroughly chilled to refrigeration temperature? Or does it have more to do with the fact that the knife has gotten warmed up from cutting hot proteins?


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## SpikeC (Apr 7, 2012)

The warmer the surface the faster the reaction, basic chemistry. Freshly cooked chicken makes blue much faster than raw chicken or cold cooked.


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## Eamon Burke (Apr 7, 2012)

If I cut about 50 lbs of sweet potatoes at one time, it turns my shig purple.


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## skewed (Apr 7, 2012)

Since it hasn't been mentioned: ham= blue/yellow.


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## Keith Neal (Apr 7, 2012)

99Limited said:


> It seems that acidic items turn carbon knives shades of black and proteins turn them blue. What I'm wondering as far as proteins go, does fish have the same effect as beef and what effect does raw versus cooked make. Would you get the same colorization from cutting proteins that were hot from being cooked as you would from cutting proteins that were cooked, but had been thoroughly chilled to refrigeration temperature? Or does it have more to do with the fact that the knife has gotten warmed up from cutting hot proteins?



I have been using my Masamoto shiro ko hongasumi yanagiba to cut sashimi perhaps once a week for a year with no hint of patina. Mostly tuna, but a few other species.


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## slowtyper (Apr 7, 2012)

I get a pretty strong blue/purple patina when cutting green onions and cucumbers on my usuba. That is my favourite patina.


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## tk59 (Apr 7, 2012)

BurkeCutlery said:


> If I cut about 50 lbs of sweet potatoes at one time, it turns my shig purple.


Mangos seem to get things purple, too.


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## chinacats (Apr 8, 2012)

I enjoy the color that pineapple gives my suji--kind of light blue:>)


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## macmiddlebrooks (Apr 8, 2012)

My Kono fuji was very reactive at first (esp. onions) and now sports alot of ochres and yellows mixed with grey. Now it's stable and I've grown to love the subtle colorings.


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## K-Fed (Apr 8, 2012)

Very nice. I've always thought that the Kono fuji is one sexy knife. Add a little patina and a custom handle and whoa....


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## macmiddlebrooks (Apr 8, 2012)

I haven't used nearly as many high-end J-knives as many on this forum, but it stands as my favorite by far....it's just a "goldilocks" workhorse for me. I don't see myself looking for anything else (at least for a couple years) gyuto-wise.


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## tk59 (Apr 8, 2012)

bananas also give a purple patina


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## James (Apr 9, 2012)

tuna steaks and salami give me a very deep purple/blue


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## bieniek (Apr 9, 2012)

Using knife hard gives black patina


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## jmforge (Apr 9, 2012)

Leaving it in the sink would give it a lovely orange patina?:rofl2: But seriously, ladies and germs.....how long do you leave mustard on a blade to get a forced patina?


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## Lucretia (Apr 9, 2012)

Here's Wayne Goddard's mustard patina technique. Page 60 has the what to use/how long information.


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## bieniek (Apr 9, 2012)

I just did it this morning with my project cleaver, i first submerged blade in hot water, took out, wiped it a little, the blade hot is quickly drying, then I applied dijon- apple cider vinegar mixture on the blade, and wait just long enough for the mixture to dry out. Maybe 30 seconds? I repeated it 10 times. The rest comes with time.

Thanks Lucretia, have to check this out.


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## Pensacola Tiger (Apr 9, 2012)

Another forced patina technique was shared by Øivind's friend Harald (Darkhoek) in his blog:

http://*****************.com/2011/01/forcing-patina-on-shigefusa-240-kasumi.html



bieniek said:


> I just did it this morning with my project cleaver, i first submerged blade in hot water, took out, wiped it a little, the blade hot is quickly drying, then I applied dijon- apple cider vinegar mixture on the blade, and wait just long enough for the mixture to dry out. Maybe 30 seconds? I repeated it 10 times. The rest comes with time.
> 
> Thanks Lucretia, have to check this out.


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