Verdigris

[Der Gebirgsjager]

You know--that green stuff on brass that is said to be poisonous. Over the years it's given me lots of grief, especially the brass hooks on rifle slings. I can put them away all nice and clean, and then take them out a couple of years later and the stuff is so thick one can scrape it off with a pocket knife. Caused, apparently, by the tanning acid remaining in the leather.

I've tried lots of things over the years to try and prevent it, like coating the brass with lacquer, coating it with grease, coating it with wax, and nothing seems to work. I consulted a friend about it who is in the leather business and he doesn't know how to stop it.

Does anyone here have the answer?

[lefty o]

clear paint.

[Der Gebirgsjager]

Tell me more. I didn't know there was such a thing as clear paint. I've used clear lacquer, and painted it on with a brush. :?:

[lefty o]

its paint with no pigment in it=clear. if you need stronger, clear powder coat.

[JWT]

My M1 Garand and M1A slings just have a bit of tarnish after 20yrs in a safe in my basement. I only added the golden rod a couple of years ago. How's the humidity in your storage location? Do you have any desiccants that could be outgassing anything?

[JSnover]

How's the humidity in your storage location? Do you have any desiccants that could be outgassing anything?
That would be my first guess. Unless I'm wrong, verdigris is caused by mold spores and humidity. On wood or leather you'll get grey fuzz but on copper or brass you'll get a green funk.

[Der Gebirgsjager]

My M1 Garand and M1A slings just have a bit of tarnish after 20yrs in a safe in my basement. I only added the golden rod a couple of years ago. How's the humidity in your storage location? Do you have any desiccants that could be outgassing anything?

Well--I don't quite know the answer. The guns are stored inside a heated building in the cheap plastic black gun hard cases. They are in either thick plastic bags or Brownell's silver colored metallic bags with no rust paper. The paper emits a vapor that drives moisture away I believe. I really think it's a chemical reaction with the leather tanning acids, but can't prove it. But--maybe it's a reaction with the chemical in the paper. Interesting that no one else seems to experience this problem to the extent I do. Must be an answer. I know that the slings had brass hooks until late in WW II when they changed to steel because of brass being a strategic material. The steel hooks will rust if not treated, so I guess you take your choice. Green corrosion or rust.

[lefty o]

leather slings should not be stored with guns, nothing good will come from it.

[Der Gebirgsjager]

Probably true. But even the ones that I have that aren't mounted on a rifle turn green.

[lefty o]

leather holds moisture, plus whatever chemicals it was tanned with.

[izzyjoe]

I learned on this stuff years ago, when I left cartridges in the loops of my gun belt. I removed the green crude with steel wool, and now the only time I load them up is when take my SBH hunting or to the range. And with military slings that ain't something you want to be taking off and on, unless they have quick detach swivels. I just wipe the green stuff off the best I can and roll on.

[Ballistics in Scotland]

It is indeed caused by acids left in the leather, and would be worsened by a damp or marine atmosphere, but is unlikely to be eliminated without them.

I hear they are calling clear paint varnish nowadays. It might help with things that touch leather lightly, car lacquer probably being the best, but I think sling swivels would wear through it.

You might make some improvement if you soak the end of the sling in water for a while, not hotter than you would wash a baby in. The use of saddle soap would leave behind substances such as lanolin and beeswax which would reduce moisture absorption. I've had the same steel swivels on a sling I treated liberally with neat's foot oil s ome forty years ago, with no rust. It should be good quality, as some brands contain mineral oils, which can harm the stitching of leather goods. Mink oil might also be good.

I also have a very old knife sheath which I treated about equally long ago with mucilin, which I think is a trade name in the UK for a silicon synthetic grease used to make fly-fishing lines water-repellent, and thus float on the surface film. That has been stored in some humid locations with no corrosion, but again only with steel.

[Der Gebirgsjager]

Thanks for the advice. I brought steel hooks and rivets just to illustrate my frustration, but actually have only a couple and that's pretty well under control. But as for the brass, so far the advice of izzyjoe (above) to "just wipe it off and roll on" seems to be where I'm at. I have used some of your suggested items, saddle soap, neats foot oil, also wax, Vaseline, mink oil and have painted clear lacquer on the brass with artist's brushes. I still have most of these products on my shelves in my shop. All to no avail, I might add.

One concern I've had is not to cause the leather to deteriorate. I'm a bit reluctant to try the soaking idea, as the slings are stored on the guns and moisture persists. Perhaps lefty o's axiom that "leather slings should not be stored with guns, nothing good will come from it" is sound advice, but at this point I have many such and it will take a while to correct. Also, once removed from the rifles and kept elsewhere they will doubtless continue to corrode.

Many of the products you suggested, BIS, I have also used on leather in the attempt to counteract mildew. Mildew is not a general problem here, but I have encountered it twice on holsters imported from Europe, the one immediately coming to mind an otherwise new appearing holster for a CZ 52. It seems like absolutely nothing will kill the stuff. One can use, for example, mink oil and get all of the visible mildew wiped off, but just a month or two later and it will be white again. The best treatment has seemed to be Vaseline, perhaps because it is thick and seals the surface from the air, but again it will reappear eventually. The CZ's holster was almost new in appearance when received, but the color is now approaching black from applications of stuff that didn't work.

It is interesting though, that as my leather working friend told me several years ago, there just doesn't seem to be any well known answer to the verdigris problem. I know it's been a problem for many years, and it's my understanding that it is why they began to nickel plate pistol cartridge cases that were likely to see extended carry on police belts. It is definitely a brass/leather problem, as the numerous web Lee Enfield slings I possess that have brass keepers show no corrosion at all.

It would seem to be one of those problems in life for which there is no satisfactory answer. One idea has come to me though-- I wonder how museums handle the problem? Maybe I'll contact the NRA Firearms Museum and see what they suggest. If they have an answer, other than periodic cleaning, I'll post it.

[doc1876]

I have a friend who supplies stuff for movies. His the bullets never get taken out of the rigs, and yes they turn green.
I made him several belts, and a ton of 45-70 dummys for "show". I washed all of his brass in lemon juice mixture before "loading", and this seems to work quite well.
If you coat the brass with clear lacquer, you will have serious chamber issues when you start firing. If you coat the leather with the lacquer, you will have serious cracking as time goes on. Kinda like a bunch of dominoes.................

[RogerDat]

Two ideas came to me, might be brilliant or could be proof I should have second cup of coffee before I post.

1).
What about citric acid (canning salts) wash for the brass swivels? I brief wash in water and a small amount of citric acid is done for brass cases to passivate the brass so that it will resist tarnishing during storage.

Google passivate brass. Or do a google site search here. Essentially reacts with the brass to form an invisible layer that is no longer reactive. I can't say I ever dug into chemistry deeply but sort of figured it was like the tarnish on aluminum, that surface layer of tarnish on aluminum ties up the molecules and blocks further oxidization of the aluminum.

Citric Acid is available online or locally where they have canning supplies, around here that means grocery store. Some hardware stores might also have it. Comes in a plastic bottle like spices come in, you know shaker on one side, pour opening on the other. I did around 6k rounds of .223 and used less than a bottle of citric acid.

Would have to putting it on swivels cleaned of other coatings so it could react with the brass.

2).
What about thin clear plastic tubing over the metal. Like a hobby store might sell as fuel line for model, or maybe a pet store for aquarium air line. Cut to length then split down one side to allow sipping it on the sling. Physical barrier between leather and brass, might not be too visible left on, or could just be slipped off for "dress" occasions.

Might even find it at big box home improvement or auto parts store, know I have bought larger clear plastic tubing there. Or small engine shop, fuel line for a gas trimmer / weed wacker is about size I am thinking of. Take care splitting the hose lengthwise so it can be slipped on. That is some detail work with a sharp razor but if truly it is the leather touching the brass, hose should prevent that contact.

As an aside I heard the same thing about nickel cases, done so brass cases wouldn't tarnish from being left in loops on leather belt.

[Der Gebirgsjager]

Thanks for the responses. Whether or not citric acid might or might not prevent the verdigris in the future, it might slow it down, and might help greatly in the clean up. Another possibility is that nickel plating the parts might prevent reoccurrence, but it is probably impossible to plate the rivets that are already in the leather, or beneath the hooks where they are riveted to the leather. These are all "Hunter" brand slings that I bought in quantity at one point. Actual military issue slings have the same problem, but not as severe. Still hoping to hear back from the NRA Museum.

[w5pv]

Have you tried treating the leather with neatsfoot oil,I treat all of my leather with the neatsfoot oil and have never noticed any tarnish on the metal parts.It may have been there but I never noticed it.It will cause the leather to get softer and stretch some but it will keep it from drying and cracking.After getting it treated a couple of times is all you need to treat it again is when it starts to dry out.

[bigdog454]

Clear fingernail polish works great!
BD