Many moons ago, I inherited some coins and paper money from my mother-in-law. Her husband was in the great war and brought some pocket change home with him. So she became interested in coins and began collecting Mercury's, Nickels and Wheat's. Memorial cents followed, including this 1982 Lincoln Cent Collection, encased in a thick paper product, enclosed in a plastic display case. Anyone out there have any idea what may have happened to these coins and why? Is there any way to remove the green crusty matter that crept in from the edges.(only on some of them). Or just let them be. Is whatever value they may have had been diminished due to their current condition. HELP!!
I wonder if either the plastic is PVC, or if the paper has sulfur and its green toning starting. Either way, you will never get a shiny original cent back.
I appreciate the feedback. Seems like the Copper pennies were not as affected as the Zinc pennies were.
It looks like the 4 zinc cents have started to oxidize. There is no returning to a better condition. Remove the coins and do not reuse the cardboard holder. If it has any sentimental value and you keep it, store away from other coins. Sets of these coins can be found on ebay in nice condition.
Zinc Cents are actually Copper Plated Zinc planchets. Both copper and Copper plated zinc were use in 1982. With 7 varieties as shown. When the copper plating is compromised the inner zinc starts to rot.
Could this have happened to the coins because she lived in southwest Florida and probably her condo got more warm and humid when she traveled?
Probably all the zinc cents are turning green. What you have was designed and sold for a novelty item to Unsuspecting people. They’re only worth seven cents.
Its exactly how it happened. Copper and zinc are disimilar metals. If the zinc is even minutely exposed to the air from a scratch or nick in the copper plating it will dust over with a thin layer of zinc oxide over the exposed zinc to protect it from the air sacrificing a surface layer to zinc oxide. Around the rim is the most likely place for this from the strike and retaining collar and ejection for there to be a bit of exposed zinc. Now, if you add moisture between the two metals, the moisture acts as an electrolyte. You now have a galvanic cell. The copper is a cathode, the zinc the anode, and the moisture the electrolyte. This will cause rapid corrosion of the zinc into zinc oxide, well technically mineralized zinc oxide crystals (the crust you see). to stop this from happening they have to be kept moisture free. No electrolyte, no galvanic reaction. But it's easier said than done in Florida where indoor humidity rarely falls below 45% and outdoor humidity is usually towards the 90% and indoor can spike quite easily. This can be achieved through moisture absorbers in your storage area and checking them and changing them out. Ideally storing your zincolns in a confined space most of the time that's easy to remove the moisture from. Once it's started though the damage is done and there's no salvaging it. Luckily those 1982 cents are pretty common and you can replace the zinc ones cheaply. It wasn't the card or the packaging that did it, at best it would have toned the copper if it was one of those or possibly even PVC contamination which would be a slime type thing. This was caused by storing them in a high humidity environment for too long. A day or two is not a big deal but over time the effects become apparent and the time for the AC to pull the humidity out of all the nooks and crannies of a house or apartment takes forever like a place where someone would store something like this like a drawer or closet or cabinet. I deal with hurricanes and power outages that can last weeks in south Florida myself. I use the big buckets of damp rid and open everything up in the room. Its what I do. In no time at all the humidity would makes everything damp and in a month or so clothes start getting moldy from it and youll find even mushrooms growing.This kind of moisture is a sure sign that your zincolns are at risk, As well as everything else you own that's wood or fabric. It doesn't happen all at once but each incident has its effect and it's cumulative. So if someone were shutting off their A/C to go to work each day and turning it on when they get home it's not working 8-10 hours removing the humidity and moisture from the space and while it might get a little musty you might not notice anything severe. However you zincolns are getting short bursts of galvanic reactions day after day. Anyways. Thought I'd share. Being in Florida I've researched "zinc rot" extensively trying to figure out how to stop it in its tracks and have been successful in protecting my split plating zincolns examples (which are sort of my canary in the coal mine so to speak) they have the most exposed zinc, so if it starts happening I'll see it there first but I never shut off my central AC and if the powers out for a decent amount of time I'll crack open some damp rids and stick them around and open up the closets and drawers and stuff to keep it from building up. Such a pain but it's better than washing everything in the house to get rid of the musty smells and mold that will be next, not to mention the corroded zincolns that once we're pretty coins that you find looking at them 10-20 years later when you get around to looking at them again.
The “creeping Crud” is a sign of sulphuric in the paper. Suggest you remove them from the holder. Stay Safe
As I recall when these came out some varieties were bringing a premium and many collectors wanted to know how to tell the differences in the varieties. Tarnished or not this set still fulfills that purpose. Nowadays the price differences have leveled out. Tarnish likely caused by chemicals in the card stock. Keep the set together.
not to step on anyone's toes in their diagnosis, but blowing up the pictures on a desktop, it's very clear this is zinc oxidization or "zinc rot". the pictures get blurrier when I blew them up even larger and I dont' have the skill to fix it, but it's definitely zinc rot and exposed zinc and copper plating is coming off because the zinc under it is corroding. none of the copper has toned much, on either of the metal compositions. if it were a chemical doing it there would be far more toning of the copper after 39 years of sitting in it or even 10 years. these are all still Red to red/brown range.
Thanks for the chemistry lesson regarding copper and zinc, and how humidity can cause the elements to react.
