What makes a natural patina?

It is funny, well odd, that whenever this topic comes up it discloses how different my understanding of patina is compared to others. I'm not saying anyone else is wrong just that my experiences sometimes are completely different.

For instance in my experience patina is not rust. Period. As a matter of fact the things that cause a good patina will stop pitting and rust in its tracks. I've got a particularly good example of a knife that has pitted almost out of the box and a good patina stabilized it... Over 10 years and counting now.

I think a lot of what I consider stain others consider patina maybe. What I call patina is usually almost white. At least a very light grey. And a good one alters the surface to where it is no longer mirrored. Reflections through it are burnished, like a glass headed surface.

I've got an excellent example of this in my pocket. Need to get a photo up one day.

Anyway all I'm saying is that pthe term patina covers a lot of ground. I'm not sure it is as cut and dried as we think it is.

Will
 
Hehe, yeah I guess so. I should see if I can't do that soon. The knife I am carrying today has an almost white patina covering the entire blade. But after using it to tidy up some apples my wife and I put up last week it has a dark almost black streak across its middle.

Here's the thing though, I could remove the black stain with 3 in 1 oil and a few minutes work. But the underlying white patina? Much more difficult. And if I did remove it (I've done this on other knives) the surface would have lost a good bit of its mirror finish.

Will
 
I am very interested in seeing an example of what you consider this white patina. I have always been curious what causes the most corrosion resistant patinas. What do you think in your environment is giving you the white effect?
 
PNWJimbo said:
I am very interested in seeing an example of what you consider this white patina. I have always been curious what causes the most corrosion resistant patinas. What do you think in your environment is giving you the white effect?
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I agree, I'd love to see this white patina. I've only seen blades get darker with use as the patina forms.
 
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OK. Now you see the coloring of the ends? That exists on the entire blade. In the sun or bright light it is almost white. The whole blade was this white color until I used the knife to do up some apples. Now that white patina is covered with this black stain. But a few minutes with a detergent oil like 3 in 1 will strip that black off. But it takes a lot more work to take off the underlying patina.

Looking at reflections on the blade is like looking thru a frosted window pane. Nothing is sharp or well focused. The surface of the blade has been altered and is no longer polished and smooth. It is slightly burnished you could say.

This is a heavy, HEAVY, patina. It takes a lot of use in the right environment to make it form. Filet and clean dozens, maybe hundreds of fish. Whittle for hours with green wood. Core and peel a few bushels of apples and peaches. Process and slice up a couple deer. Use it as your kitchen knife when making your Saturday football chili a dozen times.... That kind of thing.

If you strip your darkened blade there should be a light gray to white surface bonded right to the metal. Most knives with a patina have at least a glimmer of this. Very few I've seen have the level of it that this one has. Old kitchen knives almost all do.

Maybe it should be called the kitchen knife patina?

Will
 
Yes thanks for the pics. Was watching a video about a 47 viper when this guy started discussing his "natural" patina vs a forced one. I feel like i can start to see some lighter, whiter areas on his knife starting to come through.

Also, did you just say you process deer with that guy? :eek:

[video]https://youtu.be/xbS5z39Norg?t=8m[/video]
 
DrPenguin said:
It is funny, well odd, that whenever this topic comes up it discloses how different my understanding of patina is compared to others. I'm not saying anyone else is wrong just that my experiences sometimes are completely different.

For instance in my experience patina is not rust. Period. As a matter of fact the things that cause a good patina will stop pitting and rust in its tracks. I've got a particularly good example of a knife that has pitted almost out of the box and a good patina stabilized it... Over 10 years and counting now.

I think a lot of what I consider stain others consider patina maybe. What I call patina is usually almost white. At least a very light grey. And a good one alters the surface to where it is no longer mirrored. Reflections through it are burnished, like a glass headed surface.

I've got an excellent example of this in my pocket. Need to get a photo up one day.

Anyway all I'm saying is that pthe term patina covers a lot of ground. I'm not sure it is as cut and dried as we think it is.

Will
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There seems to be some sort of mystical belief regarding patina online. But the science is readily available online for anyone interested in learning it. This is a very basic summary that may be somewhat helpful for explaining the phenomenon you described.

"Most metals are oxidized by the oxygen in air. This process is called corrosion. Electrons leap from the metal to the oxygen molecules. The negative oxygen ions which are thus formed penetrate into the metal, causing the growth of an oxide surface. As the oxide layer grows the rate of electron transfer decreases. The corrosion stops and the metal is made passive. The oxidation process may continue, however, if the electrons succeed in entering the metal through cracks or impurities in the metal or if the oxide layer is dissolved."

The word rust can be used to describe different oxides: Fe2O3•H2O (red rust), FeO(OH)H2O (yellow rust), Fe2O3 (brown rust), Fe3O4 (black rust) etc
 
and if you dont like it, there is always flitz and you can let it start again
 
PNWJimbo said:
Also, did you just say you process deer with that guy? :eek:
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Actually this knife did get used to process a couple deer this year. Like most hunters I have a dedicated field knife (bark river) and a seperate processing knife (a wonderful Queen trapper). But this one got used a lot this year as well. I was experimenting to see if it's size was a hindrance. At times it was to be honest.

But I used it quite a bit. It is best on small game and panfish where the thin grind California clip really shines.

Will
 
I think my 47 above could be very useful for certain tasks with its unique hawkbill shape... I will definitely have it in a vest pocket all hunting season now to add more "natural" patina to it ;)
 
supratentorial said:
"patina" is a romantic description of oxidation. For marketing purposes it sounds better than "corrosion" or "rust".



The vast majority of old knives that are shiny have been resurfaced with abrasives. Knives with original crocus or glazed finishes are fluffed and buffed if they have a dot of oxidation on them since the people with the most money to spend want shiny knives and either don't care about original finish or don't recognize the difference. Original finish is so uncommon, a lot of new collectors might not have ever seen original finish.

Condition doesn't necessarily indicate use. I've seen completely unused knives that were stored poorly and were severely damaged by rust.
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Very true, original condition is almost never seen. Storage and non use can and will cause spotting etc. It's interesting to ask if 'pepper spots' are actually islands of patina on an original sea:D Why not call them patina spots then?;)

Sometime back, I got upbraided by steel experts for saying patina is a type of nascent rust, but I still regard it as such because it's a natural oxidation process. Ideal patina should cover the knife evenly, but seldom does (the tang being near oil obviously resists this) . Attractive patina is caused by constant use and is thus a WIP. Stop using the same knife for a while and its patina will become duller and the metamorphosis to rusting proper may be starting, albeit slowly.

But the word 'patina' is in itself interesting and is indeed shrouded in a kind of mystique and reverence in some knife quarters. Actually, it could be viewed as a euphemism. For instance, in the world of antiquities or art it has a pleasant flavour -associated with ageing and authenticity. Such notions can get transferred to vintage cars, where leather interiors are sometimes deemed as having the 'correct patina' Quite often though, these are euphemisms for worn-out, tatty, filthy! :eek::barf: If you talked about a knife being 'tarnished' people might shie away from it but talk patina and the approval rate goes up. But, it is tarnish, either from use or exposure to elements.

What will accelerate patina is much discussed, basically organic wet materials: raw meats, blood, foodstuffs bring it on fast. Use your knife to only cut dry wood or paper, twine etc and not much will form in the absence of humidity or hand 'contamination' Last night I stuck an unused Tidioute blade into a Peach, the result was nearly jet black except for the tang which was left out of the fruit (bang goes the re-sale value1 who cares?) Many people would love this colour, but I polished it off, some streaks and ghosting remain but it should make a good platform for an even patina from food use. However, I have to admit that I'm getting less and less thrilled by the whole business of 'patina' I just keep think of it in relation to smiling-knife's signature "rust never sleeps" :eek::D it certainly doesn't Carbon steel's innate tendency to vanish into rust is unnerving! Hurrah for decent stainless:thumbup:
 
I am one of those who does quietly cough and maybe emit a slight ~ahem~ when someone calls patina rust. But I don't get upset about it. 😊

I agree wholeheartedly about it being a WIP. That is true the changes are more subtle on a well patina'd knife.

Another point about the qualifier "natural" exists for me. I've always felt that intentionally using the knife in the kitchen when other knives are better suited is kind of cheating. I know it's silly but the term natural implies to me that the knife is being used for tasks it is well suited for. Again, silly. I agree.

This GEC slim is the only pocket knife I have owned that has a grind and blade height that makes it suitable for kitchen tasks. It is like a little paring knife. I used it to core a bushel of tomatoes this morning for my wife as we put some up. I didn't use the knife because I wanted patina but because it is the best knife for that job in the house.

I don't know that it makes a bit of difference but I wouldn't hesitate to call what this knife has a "natural patina". If I had used a knife not well suited for the job I am not sure if feel that way. Silly. I agree but there it is lol.

Will
 
When I was a student, I volunteered to judge the local elementary school science fair and putting metals in different liquids was a pretty popular entry. A quick Google search brought up an example: http://www.finishing.com/78/36.shtml There are multiple bladeforums topics devoted to the discussion of patina. So that curiosity still exists in adults. Patina is even one of the most common reasons for a preference for 1095 even though the steel has other desirable properties for knife blades. I'm not sure if any marketing strategy was ever more successful than patina. ;)
 
we should live with the patina. Let's face the fact that we have never seen steel without patina.
The process happens instantly as the fresh steel is gets exposed to the athmosphere. The shine we see on the stainless blades is Cr oxyde.

By lightly polishing a carbon steel blade over time we can even out the patina layer as it forms until it is thick enough to properly shield the underlying metal from the oxygen.

Red rust is called "active" because due to it's water content it grows and flakes, exposing more metal to the oxydation, but evening out by patient polishing we have amazing examples of rust blued finishes (i.e. vintage rifles). The magnetite form (black oxyde) is more "attached" and more shielding, so it is called passive.
 
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