soak a whole knife in vinegar?

[videorecipes]

hey all, simple question for you: is it safe to soak a whole knife in vinegar to force a patina on the blade? i have a mantra and was thinking about trying to force a patina on the m4 but am loathe to disassemble the knife -- warranty and stripping screws and all that. could i just soak the whole thing in a container of vinegar or somesuch? i suspect it'd be fine as titanium and stainless steel are not terribly reactive to acid.

[ABX2011]

Can't imagine that will be good for the pivot.

[farnorthdan]

Yea I'd have to agree with ABX, soaking the pivot like that can't end well.

[attila]

Disassembly is likely not difficult, so if you don't depend on warranties, that's the wisest way to pursue a patina.

If you don't want to disassemble, dipping in vinegar may not be a problem for the amount of time it takes to patina M4. I would loosen the pivot and degrease the inside as thoroughly as possible to ensure the vinegar can act on as much of the blade as possible.

With regard to the pivot, it's most likely stainless steel, which is unaffected by vinegar if passivated already. If not passivated, vinegar may passivate it a bit, which is fine. Imagine the effect vinegar might have on a stainless steel kitchen sink.

Titanium should shrug off vinegar like water, so don't sweat that.

The only potential issue I can think of could be the bearing balls, for I don't know what alloy they are. If stainless or ceramic, they can handle a bit of vinegar. If 52100, then they may also patina if degreased.

For these reasons, I'd get Spyderco's opinion on it.

[videorecipes]

Disassembly is likely not difficult, so if you don't depend on warranties, that's the wisest way to pursue a patina.

If you don't want to disassemble, dipping in vinegar may not be a problem for the amount of time it takes to patina M4. I would loosen the pivot and degrease the inside as thoroughly as possible to ensure the vinegar can act on as much of the blade as possible.

With regard to the pivot, it's most likely stainless steel, which is unaffected by vinegar if passivated already. If not passivated, vinegar may passivate it a bit, which is fine. Imagine the effect vinegar might have on a stainless steel kitchen sink.

Titanium should shrug off vinegar like water, so don't sweat that.

The only potential issue I can think of could be the bearing balls, for I don't know what alloy they are. If stainless or ceramic, they can handle a bit of vinegar. If 52100, then they may also patina if degreased.

For these reasons, I'd get Spyderco's opinion on it.

probably the most thorough answer i've received anywhere so far -- thanks!

[zeroed4x]

One of the stupidest ideas I've ever heard.

[remnar]

Apply mustard to the blade, the blade only, and allow to sit for some time. Clean off the blade to check the level of patina and reapply mustard if you want a deeper patina. I have not done this myself but I know others have, and you can create some nice patterns if that is what you're looking for.

[harronek]

Soak a few paper towels in vinegar and wrap them around the blade only , there is no reason to dismantle the knife .

Ken

[toomzz]

get Novacan.....

[Bloke]

One of the stupidest ideas I've ever heard.

I think you're being a little harsh there, fellow.

The brother is only seeking a little advice.

[Evil D]

Don't patina the pivot, very bad idea. I did the entire blade on my old M4 Manix 2 and the pivot action sucked afterwards until I worked it enough that it wore the patina off. I could suggest dabbing the pivot hole and surrounding areas out as far as the bearings and washers extend with grease or Vaseline before soaking in vinegar. That should protect it from patina. Then when you put it back together put a new coating of bearing grease on the tang/pivot/bearings and that should be enough to keep the pivot from rust as long as you're not playing in the ocean with it.

[zeroed4x]

One of the stupidest ideas I've ever heard.

I think you're being a little harsh there, fellow.

The brother is only seeking a little advice.

Yes, perhaps you're right, my apologies.
I think the OP is wanting to add a level of "cool" to his blade and that should be respected however, the mere thought of soaking an entire knife in an acidic solution is quite disturbing.

[mb1]

I'd call forced patina functional before I labeled it as cool. I can understand wanting to protect the hidden bits too.

I just read where someone had soaked, actually boiled, their whole traditional slipjoint for 15 min in vinegar with no ill effects. Well except for stinking up the house. Different deal on a slip joint, but that's not something I would have considered doing.

[videorecipes]

I'd call forced patina functional before I labeled it as cool. I can understand wanting to protect the hidden bits too.

I just read where someone had soaked, actually boiled, their whole traditional slipjoint for 15 min in vinegar with no ill effects. Well except for stinking up the house. Different deal on a slip joint, but that's not something I would have considered doing.

yeah, i was hoping to prevent harmful rust from developing on the blade. not really aiming for something aesthetic. and we must have read the same thread about the traditional slipjoint vinegar bath -- it's what gave me the (yeah, probably stupid) idea haha.

[zeroed4x]

I'd call forced patina functional before I labeled it as cool. I can understand wanting to protect the hidden bits too.

I just read where someone had soaked, actually boiled, their whole traditional slipjoint for 15 min in vinegar with no ill effects. Well except for stinking up the house. Different deal on a slip joint, but that's not something I would have considered doing.

yeah, i was hoping to prevent harmful rust from developing on the blade. not really aiming for something aesthetic. and we must have read the same thread about the traditional slipjoint vinegar bath -- it's what gave me the (yeah, probably stupid) idea haha.

I realize that people sometimes want a patina on blades for different reasons, for looks or to help protect the surface from rust.
I'm not a knife expert but I've been around knives for quite a while and helped a few bush craft guys fix some mistakes. Patina for many bush craft guys is a badge of honor. While having the surface oxidation form a protective layer to the steel which does help protect against moisture, as the knife is used and depending upon the use, that layer will get some shallow areas and some areas that are almost completely worn off or shiny / glossy. The edge will not have deep patina obviously and that is the first area that will rust and pit. A moderate to heavy patina does not 100% guarantee that your blade will stay rust free. I've seen many knives ( not all ) that have had extensive patina from food prep and hard use and even one that was gun blued and I've removed surface rust on all of them. Some of them ended up pitted. Some of them I had to reprofile past the pitting and create an entire new edge. A few owners where confident that the patina was the end all for rust and that simply isn't true. Leaving a high carbon blade in a leather sheath ( moisture magnet ) or EDC in your sweaty pants pocket even with a heavy patina and you can have rust, most likely will get rust. You will oil your high carbon knife just as you always have or possibly face the consequences. If you're going to force a patina to your blade, I'd suggest mirror polishing the blade to keep the surface area less porous, acid etch it with your choice of vinegar based condiments and keep it oiled regardless of what you've heard.

[videorecipes]

I'd call forced patina functional before I labeled it as cool. I can understand wanting to protect the hidden bits too.

I just read where someone had soaked, actually boiled, their whole traditional slipjoint for 15 min in vinegar with no ill effects. Well except for stinking up the house. Different deal on a slip joint, but that's not something I would have considered doing.

yeah, i was hoping to prevent harmful rust from developing on the blade. not really aiming for something aesthetic. and we must have read the same thread about the traditional slipjoint vinegar bath -- it's what gave me the (yeah, probably stupid) idea haha.

I realize that people sometimes want a patina on blades for different reasons, for looks or to help protect the surface from rust.
I'm not a knife expert but I've been around knives for quite a while and helped a few bush craft guys fix some mistakes. Patina for many bush craft guys is a badge of honor. While having the surface oxidation form a protective layer to the steel which does help protect against moisture, as the knife is used and depending upon the use, that layer will get some shallow areas and some areas that are almost completely worn off or shiny / glossy. The edge will not have deep patina obviously and that is the first area that will rust and pit. A moderate to heavy patina does not 100% guarantee that your blade will stay rust free. I've seen many knives ( not all ) that have had extensive patina from food prep and hard use and even one that was gun blued and I've removed surface rust on all of them. Some of them ended up pitted. Some of them I had to reprofile past the pitting and create an entire new edge. A few owners where confident that the patina was the end all for rust and that simply isn't true. Leaving a high carbon blade in a leather sheath ( moisture magnet ) or EDC in your sweaty pants pocket even with a heavy patina and you can have rust, most likely will get rust. You will oil your high carbon knife just as you always have or possibly face the consequences. If you're going to force a patina to your blade, I'd suggest mirror polishing the blade to keep the surface area less porous, acid etch it with your choice of vinegar based condiments and keep it oiled regardless of what you've heard.

thanks for your input -- this is pretty helpful, not just for my specific question, but more broadly as well. that's why i love these forums. so much concentrated knowledge and experience!

[PayneTrain]

Smart words, Z!
Even stainless steels need a little basic care to not rust, i.e. keeping them relatively clean and dry. We never think about it, but we live in a highly corrosive atmosphere. Oxygen wants your electrons, and it will have them eventually! All we can do is slow the process with a little common sense. M4 isn't a terribly rust prone steel, not like Super Blue and friends. It won't rust unless you get reckless with it, and a patina won't let you use it like H1, so I prefer to just form one naturally to just add to the aesthetic and never assume it's more corrosion resistant than it was brand new. I guess some people like the cleaner look of a uniform patina, but I love the swirls of colors that form one lunch break at a time. :)