Old Plastic Window Envelopes In Collections

I see many auctions and even posts on this and other forums that show photos of window envelopes with the plastic window intact.

It's been a while but the plastic used on older examples has been talked about over the years and is or can be damaging to stamps, not only direct contact but fumes given off.

I've noticed that there is a higher rate of discoloration in stamps that have been stored in windowed envelopes from older collection lots that I have bought. The envelope itself sometimes has had a bit of discoloration around the window too.

I don't have many but I always carefully remove that plastic window on covers which I intend to keep. Doing this without damage to the envelope is a real chore at times.

Does anyone else do this or do you have any thoughts?

Jeff

I keep my specialty window envelopes, mounted in sheet protectors.
Removing the window for those would be damaging.
Window envelopes are part of the study of Philately.

Window envelopes for storing stamps, I just discard.

Early window envelopes were treated glassine, not plastic, and darkened with age.

I do not see any damage to the stamps thereon.