Leaving Stamps In The Plastic Bags, OK Or Not?

I have several of the U.S. yearbooks with the stamps still in their original un-opened plastic wrappers. I also make occasional purchases of other stamps from the USPS (panels, covers, etc) and have kept them in the original plastic wrap. Is it ok to store the stamps this way? They are kept in a gun safe inside my home with a de-humidifier inside the safe. Any advice is greatly appreciated. Thanks.

With an Australian bent,
Australia Post advises stamps not to be kept in some "Stamp Packs"
(Others have Mylar slips inside the packs)
Stamp Packs are a collecting discipline, so that throws a query into being.

I have noted some stamp packs breaking apart, glued edges going brown etc.

I have Stamp Packets from the 1950's the stamps inside look pristine.
I store all my covers in Polypropylene for long term storage.

I look forward to seeing what the US collectors have to say.

Over time the plastic wrap used by USPS may cause damage. I've seen it shrink with age and curl too. Although some is suppose to be archival safe, I would recommend removing them and putting them in a stock book or on stock pages.

Other stamp packs that come in glassine are ok for short or moderate term storage but can eventually become hard and will yellow with age. That will also taint the stamps. Having said that I've seen glassine envelopes that have remained good for 25 years in environmentally controlled areas. My father gave me his collection when I was starting out in 1972. A few were in H.E. Harris glassines from the mid-late 1930's that were hard and yellowed. Not having A/C growing up probably contributed to the degradation of the glassines too.

Jeff

I store in vario pages in a notebook and this seems to be a good way to store. Plastic is risky in my opinion.

If you are referring to the plastic envelope with cardboard that the USPS sends stamps out in (as pictured below), then no, it not good to keep the stamps in them. See the back of the package for the warning: "PKG NOT SUITABLE FOR PHILATELIC ARCHIVING".

Paper archivists recommend good air circulation; this keeps the paper stable.

Of course, this doesn't matter if the entire environmental conditions are poor. For example, stored on damp, unheated the basement floor.

Virtually all paper contains lignin. Lignin an organic which is found in plants and tree cell walls, it gives the cells structural strength. As the lignin breaks down, it forms acid. And when this happens, the acid begins to tone and damage the paper. This is why so many stamps still on covers shows signs of toning. Storing paper in wooden enclosures (i.e. cigar boxes) will also increase toning due to this acidification.

Poor environmental conditions really accelerates the acidification process. In many cases and even if a stamp is mounted on a 'acid free' page this can occur because lignin is still present and the buffering they applied as been consumed trying to neutralize the acids.

So the objective is to store them in a stable environmental area (65-75 F temperatures; 30-40% relative humidity) with good air circulation.
Don

Thank you all for the replies. It seems obvious that the stamps should not remain in their original shipping envelopes &/or plastic. I figured leaving them in their original un-opened state would preserve their value. However It seems that doing so, long term, may have the opposite effect. Now I will get the pleasure of opening them and putting them in binders. A few years ago I inherited my father's collection of the yearly commemorative folders and books. They include every year since the first folder issued in 1968. He put the stamps in the mounts for the first several years, but later on just left them in their envelopes &/or plastic wrap. It appears that for some of the years, the folders are harder to come by, and may be more valuable, than the stamps that came with them. Thanks agaian for the replies. :)

Interesting order that just arrived in the mail. There was nothing but the stamps; no protection at all and even though the outsid of the envelope said do not bend the postal carrier jammed it in my mailbox (live in apt.) creasing the sheets. Dunno what to do other than use them for postage