mint sets appear to have been flooded

[Dick]

I just received 5 mint sets, that have heavy mottling, and stains from water, drying on the coins. and in some cases, leaving the entire face with a whitish film. What can be done to "clean" them up? The envelopes are untouched, other than normal were, and tear from handling, etc. There are no visible holes, or tears on any of the wrappings, so how did it occur?
I thought "airtight", meant "watertight", as well. Any ideas?
Dick

[Bob P]

It is possible that the coins were left in the sun or a very humid area Dick. Sometimes, if it is humid enough, condensation will form on the inside of the plastic, and therefore affect the coins with the film you are describing. That's about the only thing I can think of.

[coop]

Or the other end of the spectrum. They may have been kept frozen and the moisture developed inside the layer of mint set. Why would some one freeze them. In the 60's things that you wanted to keep from being exposed to fire and you didn't have a safe, were stored in the freezer. I know this is true as mother always kept her stash of cash in the fridge in case of fire. Coins were kept there as well. Now days you can get a fire proof box anywhere, but were not common in the 60's. (Kind of seeling like I lived in the stone age.)