Proof And Mint Set Question

All considered, I think I'll check mine, too. They have only been in my posession for two years, but they date from the '60's on, and they have come from everywhere. Which says there is high humidity in many areas.. Best have a look. Thanks for bringing it up.
Dick

Rick, are you putting individual coins in foil or rolls, 2x2 and tubes? I guess what I am asking, is there anything between the foil and the coin itself? I would think a copper coin against foil would have some sort of reaction.
Jim

Back to the aution. Another reason for what you noticed is standard buying frenzy. Sort of like a school of sharks with only a few peices of food available. People just go nuts and bid excessively. Your lucky you left when you did. I've been collecting Proof and Uncirc sets from somewhere back in the early 50's. Not sure. All in boxes and to old and lazy to go look.
As to storing any metalic object in another metalic object. No problem as long as they don't touch. As noted disimilar metals touching actually create an electronic charge and an electron flow is generated. This is the priciple behind electronic thermocouples used in factories, power generating stations, etc. Two wires of different composition are joined in a thing called a thermohead, inserted into a thermowell in a pipe of air duct. The other end is connected to a meter. All changes in temperature move the electrons one way or the other at the point of joining allowing such changes to be monitored. A similar priciple is utilized in a Cathodic protection system for the presevation of underground metalic pipes. This is where an sacraficial anode is place in the ground to absorb electronic flows where metals touching can distroy one of them.
Using Aluminum foil to wrap coins as long as the foil isn't touching the coins is fairly safe and if done properly, can keep air out.