# Should I force a patina on new knife?



## Edgy Guy (Aug 12, 2011)

I have two new Konosuke White #2 knives.
I read the patina they eventually develop provides a small amount of rust protection. (Is this a myth?)
I've also seen videos where people use mustard (or vinegar) and water to intentionally speed up a patina.

Is there any advantage to just letting the patina develop naturally and slowly over time?

My cast iron pans have a wonderful durable non-stick finish after years of oiling/seasoning after every use.
I believe this old patina cannot be accelerated; you must be patient.
I'm wondering if people do the mustard/vinegar thing purely for cosmetic reasons - or for the health of the knife.


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## mpukas (Aug 12, 2011)

Patina on a knife is completely different to the seasoning on an old cast iron pan - that comes from long term us of cooking oil being "absorbed"a nd burned onto the surface of the iron, and not being completely washed off. Patina is a reaction from steel to acid elements in different foods. There is no build-up of a surface film. 

Forcing a patina is up to you - you can do it for aesthetic reasons, to get a certain look. Or you can do it if you find the steel is reacting to foods prior to developing a patina on it's own. However your patina comes around, it will help protect the steel from rust (somewhat but not totally) and further reacting to foods. 

I've also heard that forcing a patina w/ very acid products can actually dull a very fine edge. The acid basically eats away the fine metal. Not sure if this is really true - or even much of a concern - but makes some sense to me.


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## Edgy Guy (Aug 12, 2011)

mpukas said:


> Patina on a knife is completely different to the seasoning on an old cast iron pan - that comes from long term us of cooking oil being "absorbed"a nd burned onto the surface of the iron, and not being completely washed off. Patina is a reaction from steel to acid elements in different foods. There is no build-up of a surface film.
> 
> Forcing a patina is up to you - you can do it for aesthetic reasons, to get a certain look. Or you can do it* if you find the steel is reacting to foods prior to developing a patina on it's own*. However your patina comes around, it will help protect the steel from rust (somewhat but not totally) and further reacting to foods.
> 
> I've also heard that forcing a patina w/ very acid products can actually dull a very fine edge. The acid basically eats away the fine metal. Not sure if this is really true - or even much of a concern - but makes some sense to me.



When you wrote, "if you find the steel is reacting to foods prior to developing a patina on it's own", what is this reacting you speak of?
Isn't this *reacting* just the patina-forming process?
Or are you talking about a huge reaction, like rust?


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## obtuse (Aug 12, 2011)

I would let the patina set naturally, unless you're having rust problems. A natural patina is a beautiful thing. If a patina must be forced, I prefer phosphoric acid. Phosphoric acid reacts to iron and forms a very rust resistant oxide. The only negative with phosphoric acid, is it leaves a dull grey finish.


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## obtuse (Aug 12, 2011)

I believe he speaks of food discoloration due to reactions with the steel i.e. brown onions, sulfur like aromas.


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## stevenStefano (Aug 12, 2011)

Depends what you're cutting. If you cut a lot of onions and that, forcing a patina is a necessity unless you like red onions turning into black onions. If it's just meat and that sort of thing though I'd just let it develop naturally


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## Edgy Guy (Aug 12, 2011)

The knives will be used for everything in a home kitchen.
Are such onions, turned black, in any way unsafe to eat or just a temporary aesthetic annoyance.
This ain't no restaurant and if the family won't eat what I cook I just beat them more. :knight:


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## jmforge (Aug 12, 2011)

mpukas said:


> I've also heard that forcing a patina w/ very acid products can actually dull a very fine edge. The acid basically eats away the fine metal. Not sure if this is really true - or even much of a concern - but makes some sense to me.


 That can happen. The funny thing is that the diluted ferric chloride that most of us knifemakers use to etch damascus or highlight a hamon actually seems to etch fully hardened martensitic steel more aggressively than steel in its "softer" states. The net effect of the patina is that you either turn the "bad" orange oxides (aka rust) into the "good" black oxides as in the case of old fashioned rust blueing or you just go straight to the good ones, hopefully bypassing the orange rusting stage like you would with a modern hot or cold blueing method. Some guys alternate blobs of mustard and selenium based cold blueing paste to get an interesting effect on field knives, but I don't know that I would want to use the cold blue stuff on a kitchen knife.


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## ajhuff (Aug 12, 2011)

I vote go natural and don't worry about it. Just cut your onions quickly and wipe you knife if you start with your knives fresh outta the box. 

-AJ


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## Pensacola Tiger (Aug 12, 2011)

In my experience the Konosuke white #2 steel isn't as reactive as the SK-4 in a Fujiwara, for example. You shouldn't have any problems with food discoloration.

I used mustard on a fingertip to force a patina on it for appearance.


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## mpukas (Aug 12, 2011)

Edgy Guy said:


> When you wrote, "if you find the steel is reacting to foods prior to developing a patina on it's own", what is this reacting you speak of?
> Isn't this *reacting* just the patina-forming process?
> Or are you talking about a huge reaction, like rust?


 
Different steels reactive differently w/ different foods. Onions and cabbage are two of the biggest. Usually it's a darkening of the food you're cutting and a bad odor from the steel. 

This reacting can be part of the patina forming process, but not necessarily. Certain foods may react w/ the steel and not develop a patina. I have a Moritaka kiri-gyuto that is clad. The cladding on that knife reacts horribly w/ many foods, rusts easily, and won't take a patina at all. 

I don't have a Kono, but I have a Yusuke in white #2 - it may be the same steel, or something very similar - and I find it to be not terribly reactive or prone to rust. When I cut citrus fruits, I often rub the blade down w/ a spent half of a lime and let it sit for a while; no problems w/ rust and it get a good patina. Patina will also change with use depending on what you're cutting.


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## mpukas (Aug 12, 2011)

Check out Darkhoeks blog entry about forcing a patina on a Shigefusa. You should really read the previous entry on the gyuto shoot-out to see what happened w/ knives reacting to foods he tested. 

In my limited experience and knowledge, I find that the cladding of a knife can react to food more than the actually cutting edge, or core, metal. Many san mai knives are clad w/ cheap, soft iron or steel (don't know the varieties) that rust easily and react badly. That's why I currently prefer: A) single steel knives, like the Kono white #2 & Yusuke white #2, or some stainless or semi-stainless variety; B) clad knives that are clad in stainless or semi-stainless steel; C) clad knives that are clad in a metal that will take a patina to limit reactivity. 

This is personal - to some it may not be a big deal, but to me, as a serious home cook and private chef, it is a potential deal breaker. There are so many great knives available to us that I don't want to deal w/ a stinky knife and black cabbage in front of clients and friends.


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## tk59 (Aug 12, 2011)

A few knives really give a strong odor and flavor and react quickly. Any steel that has very low impurities (esp sulfur) will be fine with constant wiping, initially and then much less once the patina is developed. As for the edge deterioration, yes, acid dulls your edge. However, once the patina forms on the rest of the knife, you will eventually sharpen the edge and keep the rest of the patinated surface. I cut a lot of acidic materials and a lot of carbon steels definitely lose their super keen edges fairly quickly. However, they also sharpen up very easily.


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## TamanegiKin (Aug 12, 2011)

I've forced a patina or two using mustard or vinegar. You can get creative with forcing a patina, my konosuke gyuto is currently sporting a dabbed mustard patina. I'm probably going to remove it though and trim up a bunch of rib eyes this weekend. I believe there are a couple threads in here discussing the influence of different foods on building patina. From what I've gathered blood works well.


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## jmforge (Aug 12, 2011)

Are there any particular carbon steels that you guys have found are too reactive as a general rule?


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## SpikeC (Aug 12, 2011)

I do mustard on my O1 blades for the consistency of it. Meat juices work, butt it ends up being a bit random, which isn't bad in itself. The various elements that contribute to the patina blend with the mustard patina in my experience, and result in a mellow look.


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## Mattias504 (Aug 12, 2011)

I haven't read the other replies yet but I say do not force a patina. I find that you get better results just letting it happen over time. I prefer natural patina over forced every time.


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## Cadillac J (Aug 12, 2011)

I would wipe your knives down with acetone first, as both of my Kono white#2 had some lacquer on them that wouldn't let the patina develop fully.

Personally, I always let my patina develop naturally...you can just buy a cheap bag of cooking onions and go to town to get it started.


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## RRLOVER (Aug 12, 2011)

Cadillac J said:


> I would wipe your knives down with acetone first, as both of my Kono white#2 had some lacquer on them that wouldn't let the patina develop fully.
> 
> Personally, I always let my patina develop naturally...you can just buy a cheap bag of cooking onions and go to town to get it started.


 
+1.....Sacrifice some cheap produce.


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## Vertigo (Aug 13, 2011)

Yeah, I haven't used a Konosuke but I'm willing to bet, if it's anything like other higher-end White #2 knives, that you won't have discoloration on food. Nor will the steel itself be so reactive you really need to worry a lot about rust--I say cook yourself a lot of red meat for the next few weeks and "persuade" the patina.


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## Edgy Guy (Aug 13, 2011)

Vertigo said:


> Yeah, I haven't used a Konosuke but I'm willing to bet, if it's anything like other higher-end White #2 knives, that you won't have discoloration on food. Nor will the steel itself be so reactive you really need to worry a lot about rust--I say cook yourself a lot of red meat for the next few weeks and "persuade" the patina.


 
How does cooking red meat "persuade" the patina?

It's not a trap.
I'm not cool.
Honest question from someone with 2 weeks of experience and only 35 posts.


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## Vertigo (Aug 13, 2011)

The patina you get from meat has a funky bluish tint. Looks nice, and is a good base coat for the things to come.


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## JohnnyChance (Aug 13, 2011)

Different types of food cause different patinas to form. Medium-rare beef or duck, medium pork, cured but uncooked bacon (and other similar proteins) all produce blueish patinas that set in really well.


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## Vertigo (Aug 13, 2011)

The blue streaks on this guy:


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## Edgy Guy (Aug 13, 2011)

Great pics Jonny and Vertigo.
Thanks guys.

Hey, I should start a thread for Patina Pics.


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## sachem allison (Aug 13, 2011)

I find that if I cut twenty pounds of Idaho Potatoes into french fries and leave the residual starch on the blade for about an hour or so and then rinse it of with cold water and my fingers my blade gets a very light beautiful blue grey patina on the blade. It last for quite a long time and only gets better with age. I don't have to worry about acid eating the edge. Apparently the same browning agent that oxidizes the potato will oxidize the knife. Some old time gun makers use to use potatoes to brown their barrels because it was less harsh and poisonous than the chemicals available, it takes time but its worth it. 240mm Hiromoto carbon gyuto


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## ecchef (Aug 13, 2011)

Edgy Guy said:


> Great pics Jonny and Vertigo.
> Thanks guys.
> 
> Hey, I should start a thread for Patina Pics.


 
Jim's already got one up & running:

http://www.kitchenknifeforums.com/s.................................A-patina-thread.


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## Wagstaff (Aug 13, 2011)

sachem allison said:


> I find that if I cut twenty pounds of Idaho Potatoes into french fries and leave the residual starch on the blade for about an hour or so and then rinse it of with cold water and my fingers my blade gets a very light beautiful blue grey patina on the blade. It last for quite a long time and only gets better with age. I don't have to worry about acid eating the edge. Apparently the same browning agent that oxidizes the potato will oxidize the knife. Some old time gun makers use to use potatoes to brown their barrels because it was less harsh and poisonous than the chemicals available, it takes time but its worth it. 240mm Hiromoto carbon gyuto



I'm glad someone else pointed this out. I've read so many patina threads without seeing it... started to think I was a bit crazy but as a n00b/veggie I should be quiet. I've "grown" and destroyed a few patinas over time on French carbons. A rather pretty, colorful one comes from potatoes and maybe even prettier from sweet potatoes. It probably is a lot slower than from cutting bloody meat, though.


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## Edgy Guy (Aug 13, 2011)

Would not covering the blade in a puree of one raw potato for 20 minutes (or the time it takes to cut 20 pounds into french fries) have the same effect?
I'd hate to waste all that food.

Maybe I'll do some experimenting with sweet potato puree, take a pic, clean the blade off with Flitz, then start over with another food and take more pics.
Better yet, I could apply one inch of one food, the next inch of another food.
A 10" blade could accommodate 10 different "paints" - actually 20 if I use both sides.

I'm also an artist and the idea of using Hitachi White #1 as a canvas appeals to me.
It's very edgy.

So the list should include:
Blood, from beef I assume
Potato
Sweet Potato
Mustard
Vinegar

What else?
Tomato?
Citrus fruits?
Pineapple?


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## Wagstaff (Aug 13, 2011)

Edgy Guy said:


> [snip]
> 
> Maybe I'll do some experimenting with sweet potato puree, take a pic, clean the blade off with Flitz, then start over with another food and take more pics.
> Better yet, I could apply one inch of one food, the next inch of another food.
> ...


 
Ok, you're completely out of your mind, but you're my new hero.

And you take amazing pictures, so please do this and share with us!


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## Edgy Guy (Aug 13, 2011)

Wagstaff said:


> Ok, *you're completely out of your mind*, but you're my new hero.
> 
> And you take amazing pictures, so please do this and share with us!


 
Well, I like to think I'm so open minded that my brain fell out.
That would explain a lot of things in my life.

SO, y'all guyz and galz who cut stuff for a living . . . what other foods have you noticed produce attractive reactions?

Does human blood produce a different color than cow blood?
I'm not sure where I'd get human blood.
Extracting some for this purpose is too macabre, even for me.
Actually these knives are so sharp I may get some soon for free. :happy1:

It would be cool if I knew which colors result from which foods.
Then I could shoot for a rainbow by lining them up just right.

Also if blood made blue and tomato made red, could I mix them to get purple?
This could be fun.


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## SpikeC (Aug 13, 2011)

Don't forget chicken! 
An interesting thing about potatoes, if you put some in a jar with water and put a piece of rusty steel in, the rust will desolve. The contents of the jar will develop a distinktive aroma as well!


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## mc2442 (Aug 13, 2011)

"This ain't no restaurant and if the family won't eat what I cook I just beat them more."

Reminds me of a line I love...."The beatings will continue until morale improves".

I have to read all the patina threads as I am about to get my first carbon knife in the near future. An awesome looking knife from Mr. Fowler, which I believe I can safely pick mine out of the WIP due to the handle.


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## sachem allison (Aug 13, 2011)

Wagstaff said:


> I'm glad someone else pointed this out. I've read so many patina threads without seeing it... started to think I was a bit crazy but as a n00b/veggie I should be quiet. I've "grown" and destroyed a few patinas over time on French carbons. A rather pretty, colorful one comes from potatoes and maybe even prettier from sweet potatoes. It probably is a lot slower than from cutting bloody meat, though.


 
that patina starts pretty quick, I noticed with sweet potatoes I get orange blue patina which comes on strong but doesn;t last anywhere near as long as the starchy potato.


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## sachem allison (Aug 13, 2011)

Edgy Guy said:


> Would not covering the blade in a puree of one raw potato for 20 minutes (or the time it takes to cut 20 pounds into french fries) have the same effect?
> I'd hate to waste all that food.
> 
> Maybe I'll do some experimenting with sweet potato puree, take a pic, clean the blade off with Flitz, then start over with another food and take more pics.
> ...


 That would be too easy, you can always freeze the potatoes. I think you should try the whole patina as art thing and see what happens.


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## Wagstaff (Aug 14, 2011)

sachem allison said:


> that patina starts pretty quick, I noticed with sweet potatoes I get orange blue patina which comes on strong but doesn;t last anywhere near as long as the starchy potato.


 
Good point, certainly good to point out for Edgy's possible project of comparing. I find it doesn't fade completely, but it doesn't stay nearly as strong as it comes on. I spoke with Jon yesterday who also pointed out that I was referring particularly to the Sabatier Nogents, which have a carbon that may be more susceptible to a sweet potato patina than the Japanese carbons. For a couple of reasons my J-knives to date are either low-stain carbon or stainless, so I haven't really been observing the patina difference.


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