Forced Patina

Magnaminous_G said:
Others have already pointed this out, but for most users a forced Patina is not about appearance (although a well-done patina looks gorgeous) but rather about adding some corrosion resistance, and it does that very well. There are folks who etch and "antique" their knives to give it an "old" look, especially on traditional-style knives. But most people putting mustard patinas on their knives at home are trying to get a little more corrosion resistance out of them.
Click to expand...

Amen. Guys like my grandad, who came up in the Depression working as a carpenter and glass man, and hunting on the edge of the Everglades and fishing in the Florida Keys, didn't patina a knife to get a certain look. They didn't care what a tool looked like, only that it was of quality and was ready to WORK when needed. And they sure didn't care how someone else felt about how their knife looked. In fact, they'd probably just be puzzled by anyone who did care.

-- Mark
 
I have forced and not forced. The kind of knives I buy usually have decades of patina on them already. I don't do it for appearance although I will admit I have a 194ot that I forced a patina on with an onion. The rings clearly show on the blade and I like the way it looks. Sometimes I mess around with the patina for the same reason I like fiddling with my bike, or writing a song, or taking something apart to see how it works. It amazes me that 'earned' patina' is even an expression. Just being frank. It's a knife. Do what you want with it. For protection or cause you want it to look different. I don't get this argument. And we have it a lot. :confused:
 
I personally put a patina on my knives and do feel that it helps prevent the red rust. As for proper care I'd argue that a patina will not form even over time if properly cared for.It is my opinion that all patinas are therefor forced. Some just take a longer time to force a patina than others.
 
Rsmith_77 said:
and in your experience does any stainless get as sharp and keep its edge as well as carbon steel?
at least in the same price range (not sure about some of the new super steels, but they are all pretty pricey)
Click to expand...

I'd say that GEC 440 stainless is actually better than their carbon on those fronts, and the price is comparable. Wish they would offer more of their knives in it too. I do like carbon steel for outdoor tasks and I enjoy messing about with patina colours, but as smiling-knife points out in his avatar "rust never sleeps" and that's always a worry. Frankly, I dislike the taste carbon steel imparts on raw foods, doesn't matter how old the steel is or the state of its patina either it all tastes unpleasant.
 
A lot of good comments here. A forced patina however, can come off pretty easily. It's harder to rub off with fingers, but wood work will certainly strip it.
 
Sorry. We have this discussion a lot. What I don't understand is that people take affront to the forced patina issue? Not everyone does, I understand that. But some people think a patina is 'fake' if it's not earned. But we're talking about pocket knives. Should bone scales not be died? I'm not trying to argue and I got no interest in starting an argument. It just seems a weird distinction. A pocket knife can be all metal. But we fawn over ebony/bone/stag scales and pinched bolsters and blah, blah, blah. That's all about looks. So, if you force a patina - even if it is just for looks - what's the big deal. My feelings on this have changed over the years. Sorry, this was an overreaction to this topic coming up repeatedly. And it was late. I have no problem with how anyone wants to treat their knife. And I should have kept my mouth shut. This is like the oil threads on my MC forum. We can argue (sorry, discuss) this forever and it don't mean a hill of beans.

jwh said:
I thougt of this more as a discussion than an argument.

jwh
Click to expand...
 
BTW, an argument doesn't always mean a fight.


ar·gu·ment   [ahr-gyuh-muhnt]
noun
1.
an oral disagreement; verbal opposition; contention; altercation: a violent argument.
2.
a discussion involving differing points of view; debate: They were deeply involved in an argument about inflation.
3.
a process of reasoning; series of reasons: I couldn't follow his argument.
4.
a statement, reason, or fact for or against a point: This is a strong argument in favor of her theory.
5.
an address or composition intended to convince or persuade; persuasive discourse.
 
Here in the humid deep south Case CV(and others) can pit pretty fast. My hands seem to cause rust more than most on a carbon steel, but after a patina I can touch the blade for months without having to oil the blade.

I don't usually force a patina until I see a pit, or a small area of rust. A forced Patina will stop it from advancing dead in its tracks.

For example I bought this CV Copperlock at a flea market, and though it was still unused in box it had a small pit it it. Likely a spit pit from him taking it to many shows. I can't find the pit after the patina.
I did this patina on it over 2 years ago(because of the pit), and it still looks the same after cutting. I do cut fruit from time to tome, so that helps.

IMG_3735.jpg
 
Thanks folks for all of the good information and why's and why not's. There is always some interesting comments.

jwh
 
I "force" patinas on my carbon blades for multiple reasons I love the looks of a dark blackish patina and can honestly not distinguish forced patina from more natural one also being impatient I don't like to wait years for my blade to develop a natural patina. I understand that me and a large number of others also like patina because it helps prohibit more serious types of corrosion by allowing the blade to hold oil a bit better. I live in a semi-humid state and steels of all kind rust pretty badly out here even with proper and regular mantenance so I need all of the help I can get and patina is one small towards better and easier care for my blades while at the same time giving them a more earthy natural apperance so it's kind of a win win, for me anyways.
 
I guess you could say I force a patina sometimes. This is the Schrade Fire & Ice Trapper made by GEC in 1997 that I got last year (SEP 2011). I knew I would use it as a worker so I put a light application of Oxpho-Blue on the blades. Since then, I have used it for all kinds of stuff -- scraping dog stuff off my shoes, cutting hay bale strings, slicing various things (fruit, veggies, meat, etc.) at a local farmer's market for samples, cutting sandwiches in half that I get from a local gereral store, and skinning a few squirrels and quite a few rabbits along with slaughtering and butchering a pig at a friends house. I took this picture in very low light (overcast) conditions so no coloring shows per se but here's what one of my working knives looks like after about 7-months use. I carry this knife more than any other knife I have. The spey blade gets used on the animals and the clip blade gets used on the more mundane tasks.

schradedarkbonetrapper6.jpg
 
All the chemistry aside there is no arguing that I can touch a recently satin finished blade and it will rust (oil or not) and I can rub my grubby fingers all over the same blade once a good thick patina is formed with no red rust occurring. It may add to the grey/black patina but no red rust.

What is the real difference between the dark grey/black patina and red rust?

I thought the 'patina' was a layer of oxidation on the surface and red rust was actually removing/deteriorating the steel. Not a chemist BTW.

Sincerely curious though.
 
The difference in colors is due to somewhat different compounds being formed. What you get depends on the conditions under which the oxidation (rusting) takes place. (The pigment companies make iron oxide pigments in reds, greens, blacks, and yellows. But they really really tweak the conditions to get them.)

The compounds commonly formed:
Fe2O3.H2O, which is red rust
and
Fe3O4, which is black.

I don't force a patina. I use the blades and, like dropping Fizzies in a glass, I watch the magic come to pass. I like it better that way. YMMV.
 
knarfeng said:
The difference in colors is due to somewhat different compounds being formed. What you get depends on the conditions under which the oxidation (rusting) takes place. (The pigment companies make iron oxide pigments in reds, greens, blacks, and yellows. But they really really tweak the conditions to get them.)

The compounds commonly formed:
Fe2O3.H2O, which is red rust
and
Fe3O4, which is black.
Click to expand...

Thanks for posting that, and your other, earlier post as well. I have scratched my head night after night, post after post trying to figure out why folks think that starting the corrosion of a metal surface will prevent further corrosion. Never understood how staining, discoloration, and just the discoloring of microscopic rust prevents anything.

I my work I use carbon chisels, planes (power and hand), rasps, metal files, driver bits, drill bits, and on an on. Discoloring or staining them has never done a thing to prevent rust. Oxidation is not carbon steel's friend, nor any other steel.

I think this all probably started generations ago when folks stained up their blades and simply weren't able to see corrosion as readily when the blade was heavily stained. For years my oldest carbon CASE knives have plenty of hard earned patina from hard work, yet they still rust easily if they spend a day in my sweaty jeans in the middle of a hot South Texas summer.

Been that way for 50 years. They can form rust in literal hours.

knarfeng said:
I don't force a patina. I use the blades and, like dropping Fizzies in a glass, I watch the magic come to pass. I like it better that way. YMMV.
Click to expand...

Right there with you. No one wants to look like a noob, so they strive to make their knives look worn and well used. Patina and wear = history, provenance. Even CASE has seen this trend and started their pocket worn series. For me, after carrying so many well worn knives for so many years, I like them to look as new and sharp as possible. I know it won't last, so I enjoy it as long as I can.

I know that I have too many knives to ever get the kind of pocket wear my early knives got. Rounded corners, spines rounded off, jigging half gone, shields missing, etc. They went to the job site every day, sometimes for years on end with no rotation (no money!) and often little protection. I guess since I have used knives so long I like for them to earn that look, knowing that my new ones never will. That certainly doesn't mean that I enjoy my new knives any less.

I know I am being silly, but I wouldn't put a knife in an apple or cover it with mustard so it would look like my old CASE, BOKERs, EYEs and PUMAs that I have from 25 - 30 years ago.

Robert
 
A very interesting response, thank you Robert. The more so as it's based on long experience&observation.

I often polish off patina, especially when it is an ugly hue as it can be, then let it form again. Polished and well-used can look as good as patina and well used, I don't mind either so long as there's no pitting. Rust is the beginning of the end.....

All the best, Will
 
There is definitely a clear and important distinction between 'good oxidation' and 'bad oxidation'. Not all oxidation is bad, and some is naturally protective of the steel. The 'good' kind is what forms from the reaction between the iron in the steel and oxygen (only). That will very gradually darken the steel over time. It does not pit or corrode the steel in any way. It's basically inevitable and unstoppable, unless the steel is only used in a non-oxygenated environment. Even stainless steel will oxidize in a similar environment (chromium & oxygen forms a very thin and very hard chromium oxide layer, which protects against further corrosion). The 'bad' kind of oxidation is the reaction between iron and oxygen, in the presence of moisture. Produces a different chemical compound (as Frank pointed out earlier). That's rust or corrosion, which pits and therefore weakens the steel. Other forms of oxidation happen like rust, but with exposure to even harsher chemicals, like chlorides or acids. The downside of 'forcing' a patina is due to the deliberate exposure of the steel to acids (fruit juice, vinegar, etc), which can and will start some corrosion with associated pitting of the steel, unless the blade is cleaned thoroughly of the acids afterwards. The pitting of the steel just gives moisture, dirt, salts (chlorides) and acids more nooks & crannies in which to hide and further corrode the steel. This is why I think the best way to protect a blade is to polish it, and then let the 'good' oxide patina take over, with time. Polishing closes up the nooks & crannies, and a natural oxide layer on top of that does the rest. Beyond that, it's just a matter of keeping the blade clean & dry. On a highly polished blade, moisture even beads up and rolls off. That's an emphatic affirmation of how the absence of nooks & crannies prevents moisture from clinging to the blade and causing further corrosion.

The good oxide layer on a blade will not prevent rust completely. But the steel that reacts with the oxygen only, to form the oxide layer on the surface, will not react further with oxygen and water to form rust. That's why a natural patina (good oxide) helps to protect a blade from rusting as quickly.
 
Last edited:
I have read and been told (heaven forbid that is a bad start to a post :p) that one of the distinctions between patina and rust is the size of the molecule. Patina may indeed be classified as oxide but differs from true rust in that the molecule nestles neatly into the surface of the blade. Rust does not, the molecule is larger and pushes into the surface and helps flake off more material which is exposed to oxidation etc. A self feeding process.

But I am a mechanical engineer not a materials scientist. I could well be wrong.

As far as experience goes mine differs from some posted here. Once a true, long time patina is formed my knives do not tend to pit or rust to anywhere the extent that a new one does. Again, my experience is that this patina has to be a long term one. Overnight patinas seem to be very fragile and don't act the same way. Hence my conjecture that we mistake stains for patinas.

One thing I would offer to anyone switching to carbon steel: Oil will indeed keep a knife from rusting, although normal riding time in a pocket will wick it off. And once a patina is well formed it will help hold oil onto the knife surface. BUT oil itself will retard the formation of a patina in the first place. It takes time being exposed to air for a patina to solidly form. It ain't going to happen if the steel is hidden under a layer of oil.

Will
 
You must log in or register to reply here.
Back
Top