* Sealed * Mint Set Bulk Purchase

I have a 'newly-opened' box of 150 #10 envelopes right next to my computer desk and ALL of them have 'self-sealed' to some extent somehow. I have to gently pry them open before I can use them.

Coins stored in an unheated area can get cold and then if the temperature and humidity suddenly increase small amounts of water will condense on the envelope. One or two times won't do it but prolonged exposure to such conditions will. It will also damage the coins in time but they get some protection in the plastic.

It's not at all unusual for someone to seal them. A collector who acquired them in 1958 could easily have looked at the sets and sealed them to show those sets had already been seen.

They do in fact self seal and a box of 100 could have. There's no way to know but I've opened many of these packages and never found them sealed (not even self sealed). However I've seen opened packages with the sets sealed. It is quite common especially for those poorly stored. Even the closed boxes will self seal in time, I've just never seen it. I have much less experience with the oldest sets and most of what I see is 1965 and later.