Degradation of mylar?

[Gary Rosenberg <rosenberg@xxxxxxxxxxxxxxxx>]

In a posting on digital documents, B. Pettit mentioned "the degradation that
comes with time on celluloid, mylar, etc." We have been putting specimen
labels in mylar sheaths to protect them from abrasion, and to keep acidic
labels away from specimens. How long does mylar last? What are the
degradation products?  Are there alternatives to mylar?
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Gary Rosenberg                              rosenberg@say.acnatsci.org
Malacology & Invertebrate Paleontology      gopher://erato.acnatsci.org
Academy of Natural Sciences                 http://www.acnatsci.org
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