Preservation and Care of Philatelic Materials
Subsidiary Page
20
Transparent Envelopes
Transparent plastic envelopes for storing covers, postcards, blocks of four and other
multiples, booklets, souvenir sheets, and other philatelic items have been manufactured
and sold for many years. One supplier advertised and sold these as giving "complete
security and protection." They offered them as made from 5-mil archival polypropylene,
and alternately made from 5-mil, "safety vinyl." There is no such thing as vinyl that is safe
for storing stamps, covers, and other philatelic valuables. We note that the same company
no longer offers "safety vinyl" envelopes or enclosures, probably because today's collectors
can no longer be hoodwinked into buying unsafe materials.
The Arthur Salm Foundation advises that they tested transparent envelopes made by
three U.S. manufacturers. The results were:
Clear Transparent by U.S. Envelope Co. pH 5.68
"Glassine" by Worcester Envelope Co. pH 6.59
Envelope #8511 by Universal Products pH 8.14
END OF SUBSIDIARY PAGE 20
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