Forced Patina vs Cold Bluing ??

T

theyoungone

Joined
Jul 19, 2013
Messages
62
I have a few heavily used carbon blades that the black coating wore off and that I want to refinish. I have a bunch of vinegar and Birchwood Casey Cold Blue laying around. What gives more protection and will last longer on a hard use (bushcraft, hunting, food prep, yardwork) knife, a Forced Patina or Cold Bluing?
 
I don't ever "force" a patina on any of my knives. They earn their patina through use. If it wears off, just use the knife more. It'll restore itself. Cold blue works fine, but once you wear through that and get back to bare metal it will start developing a patina again.
 
Bill DeShivs said:
Cold blue offers no protection against rust.
Click to expand...


Why? Sorry - I don´t get you in that way. When you add a coating to a carbon steel blade, it will prevent from rusting. But cold bluing a blade will not save against rust? A coating (of some kind) is a coating no matter if it´s patina, bluing or even a DLC coating (or whatever).

My point of view.
 
Neither bluing nor patina is a coating per se. They are both just forms of surface oxidation. So there's nothing preventing further surface oxidation. While using one or the other of these might affect the tendency toward red iron oxide (rust) forming slightly, it won't stop it by any means.
 
Cold bluing is not oxide. It's a very light coat of copper sulphate.
 
Oops, I was thinking it was "black" iron oxide. But now I remember the blue (copper sulfate) color when applying it - it's been too long since I used cold blue - didn't care for it as it doesn't hold up well at all if you touch it. Sorry about that fellas.
 
eKretz said:
Neither bluing nor patina is a coating per se. They are both just forms of surface oxidation. So there's nothing preventing further surface oxidation. While using one or the other of these might affect the tendency toward red iron oxide (rust) forming slightly, it won't stop it by any means.
Click to expand...

Agreed - but it covers the surface (carbon steel) to prevent from enviroment influences. In the end with the same result - rustprevention


Bill DeShivs said:
Cold bluing is not oxide. It's a very light coat of copper sulphate.
Click to expand...

Yes it is, but why should it not help to prevent from rust, like you mentioned in post #4?

Sorry - I just don´t get it.
 
I don't exactly know why. In my experience, cold bluing promotes rust.
 
I like patinas. My favorite ones come from more or less stabbing a grapefruit and leaving ti there for a while. Then, over a few months of usage the patina gets added to naturally and at that point it looks super cool and gives great protection from rust. I find that grapefruit tends to leave a darker patina than mustard or vinegar and a much stronger contrast with how the fruit's flesh creates patterns.
 
In my experience it gives a little bit of protection but it isn't like a DLC coating or good paint or powdercoating. I have had knives with major patina get rusty with only a day or two outside when it rains. You still need to take care of your knife properly if you don't want it rusting.
 
I agree. "Patinas" are very much over rated. Take care of your knife and you won't need a "patina."
 
Bill DeShivs said:
I don't exactly know why. In my experience, cold bluing promotes rust.
Click to expand...

I had an old Remington 12 ga side by side that can attest to that. Cold and even hot Bluing is more cosmetic than anything else. Don't know why in the chemistry sense, other than orange rust is Fe2O3 (bad stuff that literally disintegrates carbon steel) patina is Fe3O4 (darkens the metal and inhibits the Fe2O3 from taking over). Humppa, if you need more scientific explanations, I'd recommend asking either a chemist or a metallurgist (mete, a member here can probably be more specific).
 
You must log in or register to reply here.
Back
Top