So, I'm photographing my Washingtons and when I look at the photo of this one I see little greenish/yellow blotches on the coin. I can't really seem them in hand (just barely there)...but with the camera they show up. I'm concerned they may be PVC residue. I put the coin in an acetone bath this morning just to be safe but I wanted to see what the community here thought.
I am going to be broaching the subject of PVC Contamination in an upcoming thread, so this question will serve as a good preamble. PVC contamination is usually a vivid emerald green color and even advanced PVC contamination can be removed with an extended acetone bath. Please look at the 1942-P Jefferson Nickel taken from a Harco album shown below; there are before and after photos of the acetone bath. Before Acetone bath: After Acetone bath: Now I can't definitively say that the spots on your Washington aren't PVC, but if the acetone bath doesn't remove them, then both the appearance and reaction become inconsistent with known PVC contamination.
How long of a soak would you suggest? if the spots do go away should I throw away the air tite it was in (for fear of contamination) and replace it?
Soak at least 24 hours, and then gently roll an acetone soaked q-tip over the affected area. I don't think air-tites are made of PVC, but this seems to be a situation where "better safe than sorry" might apply.
Air tires don’t have pvc in them. I was just wondering if this is pvc residue could something have off gassed in that holder that i wouldn’t want around the coin.
Silver and Cupro-Nickel will react differently to PVC's. Silver will show dull and/or white spots that can be impossible to eliminate. JMO
More than a year ago I got into a disagreement @GDJMSP over the PVC contamination. Many people blame the plasticizer in the PVC which is dioctyl phthalate. Dioctyl phthalate is a colorless, odorless viscous oil-like liquid with a very high boiling point. The odor you detect when opening a new shower curtain (or batch of 2x2 PVC flips) is actually the vinyl chloride monomer that is still present in the polymer. Doug maintained that coins stored next to plasticized (soft) PVC products would pick up the PVC residue. Since PVC is a polymer, the only way coins could pick up what we call PVC contamination is by direct contact with a PVC product or the products of decomposition of the PVC which includes HCl (Hydrogen Chloride which, when dissolved in water becomes hydrochloric acid). My thought for this contamination is that coins can pick up the plasticizer by direct contact as it "bleeds" out of the polymer. This would give a sticky coating which would be prone to pick up most anything that is around, including traces of the HCl from the decomposing PVC. The HCl could react with the coin material to give chlorides which could cause the color. Whew... Now Doug sent me a package of PVC flips on Feb. 15, 2022 and I initiated the experiment. I put the opened and fanned-out PVC flips in a larger plastic container along with a Sunshine Minting 999 silver round and a nice shiny 2015 D cent sitting on the plastic package the flips came in. I put another silver round and another 2015 D cent in a separate container and stored them in my Southern California garage. Not the most severe storage conditions, but the best I could do. I am now going to get them out and let everyone see what has happened. Stay tuned. @CamaroDMD didn't mean to hijack your post, but thought you would find this interesting. BTW, the acetone should remove the schmutz.
Fascinating info. Thanks for sharing. I look forward to seeing your results. Based on my understanding of the chemistry, the monomer makes more sense. But I’m just a silly dentist…what do I know.
Well, after a 36 hour acetone soak there is no change. So, I guess my PVC worries are no more. @Kentucky, please post your results when you have them.
I honestly don't know how it got in this thread. I was surprised myselfy when I came here and saw it, I thought I was in another thread for a minute there. I do think it's charming you of all people caught it, though.
Lol, but I think it's kind of cool you caught it. I was going to delete it because again it was inadvertent but then I figured nobody's paying any attention to it anyway so why delete it and then draw attention to why it was deleted. Then before I know it here you stumble in.
The spots may be due to sweat, spit or snot, deposited long ago. In that case, the spots will be mostly dried, denatured protein along with some salts, which may have caused some corrosion. For these biocontaminants, acetone and water rinse are unlikely to do much. Best choice is an ultrasonic cleaner with warm distilled water and a simple, chemically pure detergent. Example of a simple, chemically pure detergent is sodium lauryl sulfate … available on Amazon and cheap. Sodium lauryl sulfate is an anionic detergent (most household detergents are), so a solution of it is slightly alkaline. Therefore, coins should not be exposed to it for more than the time they spend in the ultrasonic cleaner. An alternative is a nonionic detergent such as BRIJ, Triton or Tween. They don’t have an effect on pH. Whatever you use, do a good rinse in distilled water afterward. Cal
That sounds a bit harsh to me. The spots are barely visible (some aren’t even really visible at all with the naked eye). They are far more distracting in the photo. Bring an RVD-002 (Type B) quarter, it’s also quite collectible. It’s not something I want to experiment on.
