Silicone-treated polyester film

Does anyone know if silicon coated polyester (Mylar) has a shelf
life?  I have recently encountered some that appears to be degraded.
It has a milky, streaky appearance and grimy and tacky feeling.   A
1997 DistList posting expressed some concern regarding the
cross-linking to the Mylar substrate. I have attempted to contact
manufacturers of silicon polyester to obtain more information on the
chemistry and method of manufacture, however with no avail.  I
believe that the polyester can be coated using solvents or by means
of thermal or UV curing.

Does anyone have any information regarding the processes of silicon
treated polyester?  Additionally can any supply a reliable source
for purchasing?

Sara Moy


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                  Conservation DistList Instance 20:26
                 Distributed: Monday, November 13, 2006
                       Message Id: cdl-20-26-022
                                  ***