doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Chemical reaction from guncase

Several folks in our group got into a general discussion about what case component could cause a chemical reaction to the action surface on coin finished doubles. We have (2) identical guns and cases - both actions turned black and required a professional to refinish. Note: the bluing or wood was not affected with either gun.

These (2) high grade doubles were stored in European low cost plastic trunk style cases lined with felt. The guns were stored for approximately two months with the lids of the cases open. I know that we have several chemists in our readership. What is the most logical cause of the chemical reaction - the case plastic, the felt lining, or the glue that was used to secure the felt to the plastic case. I've never heard of this type of problem before.

George, I am not certain what caused this problem, but offer a thought or two. If the case were made of vinyl material, it could be the degradation of the material causing it. Think of the coating of your windshield from the gases from the vinyl dashboard.
It could also be formaldehyde gas from the adhesive in the case.
Best,
John

Coin finish offers very little protection from oxidation or other chemical reactions. In a lot of cases coin fin is nothing more than matte surfacing on the carbon steel base metal. Perazzi offered it in the past on some of their competition guns but when I enquired about it at my latest order I was told it was discontinued due to same. I doubt you'll get a definitive answer here on the culprit.... plastic degradation, VOC's from solvents, etc. unless you can positively identify the exact plastic in the case, chemical composition of the felt and adhesive, etc.

I would first have to know exactly what "coin" finish is? I know it looks like polished steel but is it a coating, like silver perhaps? As you can see I know O about the subject, but if it were silver (tarnish) it could explain everything. Just a thought-someone enlighten me. --- John Can.

What guns were they George ?

John C is on the right track IMO. Steel that was polished would not turn black. Black is the color of silver oxidation. I would venture a guess that the guns were true silver plated thru the silver nitrate solution process. So, I think we're looking for an outgassing of something that would cause silver to oxidate inordinately fast.

George,

I'm thinking it's the guns themselves plus plain old air, not the cases. What was the make of gun?

That the cases were left open is telling. If it was the felt or felt glue, then I'd think the side of the gun touching the case would be affected much more than the side of the gun exposed to open air.

I can't think of anything that would outgas as an acid. Organics (solvents) outgas. Formaldehyde isn't going to be acidic and it's a common glue residue.

If the plastic case was PVC I truly doubt that it could degrade sufficiently to release HCl gas, which PVC will do when burned.

Two months could be enough time for unprotected silver to tarnish in South Carolina. I would think silver plated guns are rather rare though.

The original poster still hasn't answered on the gun makes. Are we dealing with modern or vintage pieces? If modern, why would a mfr. silver plate a gun receiver when there are much better looking, more durable, and cheaper finishes that look like coin? If the guns are more of a vintage type, the so-called coin finish is usually just matte polished steel. In that case the steel may have some alloying metals that make it less resistant to oxidation. For example the Chromox alloy used by A H Fox. In either case, modern or vintage, I think the resident alchemists here should forget about the black tarnishing common to silverware. I really doubt the receivers on many high grade doubles were silver plated. What are the odds of finding two with the same problem at the same time? Polished steel will definitely turn black - that's the bluing process - although it usually involves boiling & high heat to convert the ferrous oxide into ferric. I suspect another reaction is at play here but without knowing the type of plastic, felt, oil or rust preventative compound used beforehand, etc. we're all going to be shooting in the dark.

Don't leave ceratin slip-on pads on for long (even leather ones) or you will not like what you see when you take them off later!