Polyethylene deterioration

On behalf of Ginette Clement, Kateri Morin <kateri_morin [at] pch__gc__ca>
writes

>    ... Information gathered from the conservation
>    reports led us believe that in many instances the bags were made
>    in 1983 and all were done in the same lab. ...
>    ...
>    ... This would
>     suggest that this degradation is associated with the quality of
>     polyethylene sheet used.  We would appreciate any of your
>     storage stories or observations that might help us.

I am aware of vast differences in similar types of plastic film. For
example, with polyester film, ICI manufactured about two thousand
different types. While many have the same base, i.e. 3 mil (300
guage) thick, there may have been 100 or more different surface
treatments. In your case with polyethylene, the same bag maker may
have used more than one type of film because there were many films
that met their particular needs and requirements. If all of the film
was from the same batch/the same roll, and you observed these
problems, then there must be some other source to the problem.

Bill Minter
William Minter Bookbinding and Conservation, Inc.
Woodbury, PA
814-793-4020
Fax: 814-793-4045


                                  ***
                  Conservation DistList Instance 16:73
                  Distributed: Thursday, May 22, 2003
                       Message Id: cdl-16-73-005
                                  ***