So I was looking through some older UNC sets and I noticed that a decent amount of them have black spots in the inside of the gov't packaging. I'm not sure what the spots are and I was wondering if anyone would lend some advice as to what they are. I've thrown two pictures into this post for a little visual stimulation. :thumb:
Corrosion. Government sealing/packaging is not air tight and over time, environmental sulfides and moisture can enter and react. Mint sets are often collected and put away without noticing such until they get too heavy to stabalize. Jim
Oh I gotcha. I was looking at these spots and I couldn't for the life of me figure out how something would get inside a mint package. I also assumed, silly me, that the packaging would be air tight. Thanks for the info.
Pre-'85 US mint sets have a thin layer of PVC plastic inside against the coins. This is especially hard on cents and especially on 1968-P cents, all of which are now spotted. Clads and nickels are not immune and the worst of these is the '69-D quarter. Over time I expect the Ikes to be a major loser to corrosion but for now they aren't too bad. In an accelerated enviroment the Ikes look bad.
So what's the best advice for future storage of these sets. My Grandfather has close to 100 of these UNC sets, and I know their not going to pay for a house or retirement, but I don't want to ruin the coins.
Someday there will be a premium for these sets and if you do what needs to be done you won't get this premium. Personally I believe there will be a far higher premium for nice untarnished coins from the sets so it doesn't concern me a lot. I cut up many of these sets and spend the junk and low premium coins and soak the nice ones in acetone. After being properly stabilized and holdered the coins should be good for decades at least.
Is it a problem with the original cello storage, or just a problem with the general coins and how they were made? I've got a ton of these sets as well, and most are in good condition without the spots. If I were to pull them out of the cello and put them into say plastic 2x2's, will that help prevent the spots from eventually forming?
Would it be worth it to cut them up? I'd figure that if you did in fact cut them up, it would devalue the set. I guess that begs the question is it worth more tarnished in the OGP or untarnished cut up? Is there a way to store them properly without cutting the sets up?
Clad, do you think there will ever be a demand for coins of this era with mint set trademark pedigree... you know...that film that plagues this era of mint set coins?
Prime, YES! Get them out if you want to prevent spotting. Throw them in a safe with silica gel packets.
If you are archiving your coins then you want them to be airtight and moisture proof. The only way to do this is to use a Food Saver and seal your 2x2's in it. You can stack them as long as your staples, if you use them, are really flattened on both sides or do them singly. I do it and it works. As a test I soaked some coin and mint sets underwater for at least 24 hours using a brick to hold them down. They came out dry without any indication of leakage. It takes time but I enjoy it knowing they'll be look the same in +twenty years.
Apparently it's both but it's the PVC that is actually causes most of the trouble. The carbon spots on the cents might be less affected by this trigger than the other problems though. Just taking them out without stabilizing them would probably delay onset of the problem and prevent it in some coins.
At the current time most of these sets are actually worth more cut up. There are probably ways to delay onset while leaving them intact. I don't know what they are but would think it involves low humidity, stable temperature, and no weight or pressure against them. Perhaps storage on their sides would help. I've lost some really great sets to this corrosion and these things are opposite of what the affected sets were exposed to. If you catch the corrosion in the first few years most of the coins can be saved with a series of soaks in alcohol, denatured alcohol, and acetone. The longer the coins are tarnished the more difficult it is to restore them.
