I was recently asked "Should I keep my US Mint Proof Set in its original packaging and store it that way or should I take the coins out and store them individually in coin albums or coin cases?" I am asked this question on the phone or at coin shows because so many people wonder about this.
Although coins kept in their original packaging from the US Mint may appeal to some collectors, most features of the packaging are not conducive to keeping the coins looking their best for the long term. Proof sets of the 1930's and 1940's were originally packaged with coin housed in cellophane envelopes and placed inside a cardboard box. Some newer proof sets have been placed in plastic "blister packs" for ease of processing.
Original US Mint packaging is rarely air tight, which allows development of a haze or residual oil on the surface of the coin. The haze can form gradually from contact with air borne substances in the immediate environment, and can be accelerated by humidity and temperature variation. Over time, these unattractive residues not only can hide the original luster of the coin, in the most extreme cases, with the right combination of factors, they can even begin to corrode the coins!
While original Mint packaging adds some historical interest, it is simply not best for long-term coin storage. If you decide to keep some of them in their original packaging, we do offer aluminum coin proof set cases for ease of storage and organization. But if you decide to break them out of "their shells", I would suggest cleaning them off with a cotton polishing cloth, perhaps placing them in a coin capsule or coin flip, and then store them in a coin album or a coin case. This will allow you to enjoy your collection, while insuring their long term protection.
