Nega-File Glassine Envelopes

Just posting this as a glance into a "yesteryear" storage medium for stamp collectors. Found this old-timer in a stack of glassine envelopes. Anyone ever heard of the "Nega-File" storage concept?



I looked up the company and found they are still in business (under a different name and location) but still offer these size glassine envelopes, albeit quite pricey at $118 per thousand (that figures out to about 12 cents apiece.)

http://www.negafile.com/about.htm

(I would guess my glassine is representative of one of their earlier examples.)

I wish there was more than one company making them now. They have gotten expensive.

Here is pricing for the commoner sizes from their website:
#3 2-1/2" x 4-1/4" 1000/bx 40.00
#4 3-1/4" x 4-7/8" 1000/bx 52.00

Subway is $47 and $63, respectively, for those sizes. (Subway also sells them by the 100, in addition to 1,000.)

I didn't compare shipping...

Everyone notice the yellowing of the glassine?
Not good for long time storage.

Just curious...do today's glassine envelopes yellow over time as these older examples do? The example I posted has to date back to the 1940's. After 70 years of aging, it has certainly yellowed, as has most of my other glassines from that period. Is there a special process that today's glassines go through to stop the yellowing process? Or are they all destined to become yellowed after 60-70-80 years of storage?

They are all destined to deteriorate with age. Lifespan is 12-15 years I think.