Is corroded brass corrosive to steel?

[t1mpani]

I have a Puma White Hunter (old one, not stainless) that has one tiny section of its edge that keeps rusting, and holding it up to the outside of the leather sheath I see that the trouble spot lines up right with one of the brass rivets that borders the edge. Since none of the others are doing this, I'm guessing that that one rivet has something built up by it that's attacking the steel. I can't--without pulling the sheath apart--look down in there, but wondered if there was just some plain ol' green oxidation residue from the brass down there, and if that could be the problem. If so, any suggestions about what to do about it? I supposed it could be something else entirely, but whatever it is, it's localized at that one rivet.

 

[Cobalt]

The steel and brass might be acting like a cell with the brass being the cathode and the steel being the anode localized. The steel is rusting because of the contact between the two is creating this anodic cell most likely. I have not seen that happen with the brass and SS blades before

If you teflon coat both you have put a barrier between them (moisture barrier) and that should be all that is needed.

 

[t1mpani]

Hmmm, interesting idea...
I'm not sure what/how to put down in their, as I have so little room to work. I guess I can just be really diligent about keeping chapstick/wax on the edge.

And don't worry, you still haven't---this blade isn't stainless. This is an OLD SCHOOL Puma.

Thanks

 

[Cobalt]

Hmmm, interesting idea...
I'm not sure what/how to put down in their, as I have so little room to work. I guess I can just be really diligent about keeping chapstick/wax on the edge.

And don't worry, you still haven't---this blade isn't stainless. This is an OLD SCHOOL Puma.

Thanks

Reminds me of my old school childhood Puma folding knife. That little thing was awesome. Carbon steel blade sharp as a razor and I still have the scar to proove it. Sliced my finger wide open when I was 5 years old peeling an orange with it. Knifedom started early with me.:thumbup:

 

[t1mpani]

Me aswell--though I didn't start with a Puma, I'm sad to say. I had some little Barlowe that I can't remember the manufacturer of, and have no way to check since I lost it in a move from New Mexico to Virginia when I was six. First thing I did with it was cut myself, which my mother found as vindication for me being "too young" but then my father pointed out that if they had waited until I was forty before letting me touch a knife, I still would have cut myself right away, so better to get it over with.

 

[Cobalt]

Me aswell--though I didn't start with a Puma, I'm sad to say. I had some little Barlowe that I can't remember the manufacturer of, and have no way to check since I lost it in a move from New Mexico to Virginia when I was six. First thing I did with it was cut myself, which my mother found as vindication for me being "too young" but then my father pointed out that if they had waited until I was forty before letting me touch a knife, I still would have cut myself right away, so better to get it over with.

lol. Your father is a wise man

 

[STR]

Seems like anytime you get two dis-similar metals together you can start what I guess is 'galvanic' corrossion. I've even seen it where titanium and stainless were together in the wrong environment for a while. I also saw it on my LandCruiser when I rebuilt the body tub out of aluminum and mounted it to the body mounts which were steel. Inside of a year the aluminum and steel where they touched was looking pretty nasty.

For what its worth in knife making sometimes that brass corroding through the steel for like a handle just makes the handle stay on there better. But if it is where it is a moving part I'd be concerned.

STR

 

[Keith Montgomery]

By the way, it wouldn't matter if the blade was stainless. Bimetal galvanic corrosion between brass and steel (including stainless) is very common. Galvanic corrosion requires the two dissimilar metals and an electrolyte such as water that contains eloctrolytic chemicals (sweat, salt water, hard water, etc.).

 

[djolney]

That explains what is going on with my old Ka-Bar USMC: the blade and one of the staples in the sheath are pretty close, and this is the only spot on the blade that corrodes when the knife is in the sheath.

Thanks for the thread/explanations.

 

[Mikey]

I wonder if it might have something to do with the (2) metals reacting with one or more of the chemicals used to tan the leather. Just a thought.

Mikey

 

[t1mpani]

I managed to get the sheath sort of pried apart enough to shine a tiny flashlight down in it and there is no visible corrosion or buildup of anything that I can see, though that one rivet is more exposed than any of the others are, so I'm thinking you all are on the right track. At some point, I'll probably just replace the sheath (though I'll hold onto it for tradition) but until then, I'll just be sure to wax up the edge before it gets put in there.

Thanks a whole lot for your input everyone!

 

[jim n]

You should not store your knives in their sheaths, especially leather sheaths. The leather has some chemicals, tannic acid if I remember right, that will rust the steel. Clean the rust off, oil it up, maybe put some cosmoline on it, you should see not further problems.

 

[t1mpani]

You should not store your knives in their sheaths, especially leather sheaths. The leather has some chemicals, tannic acid if I remember right, that will rust the steel. Clean the rust off, oil it up, maybe put some cosmoline on it, you should see not further problems.

A good rule of thumb, but any residual tannic acid in a new sheath is dried up after two or three months, and this knife/sheath are over 30 years old. There is not a single one of my knives that doesn't live in its sheath, and I have far more carbon blades than stainless (and far more knives than any sensible person should have ). I'm simply not willing to take up twice the space to store all seperately. Brand new leather sheaths should not have knives stored in them, but beyond that as long as you make sure the blades are clean and dry after use there won't likely be problems. I know this seems like a funny statement given what this thread has been about, but this is the first time I have ever had rusting problems on one of my knives from the sheath, and you'll notice it is the brass--and not the leather--that was the culprit. I'm guessing the leather has just finally gotten old and stretched enough that the rivet became exposed, since this knife has been stored and carried in its sheath for years with nary a problem. A little wax on the edge will soon put things to right.