Distorted cellophane

Laura Wahl <lwahl [at] hagley__org> writes

>I am currently evaluating a collection of printed plastic packaging
>films, dating from approximately 1940-1970. The materials are a mix
>of cellophane, polyethylene, acetate, and possibly polyvinyl
>chloride. Many of the items are folded and cannot be safely opened
>without creating tears. ...

In contrast to another suggestion to humidify the plastic packaging
films, I would advise against contact between water and these
plastics. Cellophane and cellulose acetate degrade mainly by
hydrolysis and the polymer in polyvinyl chloride is plasticized by
water and becomes opaque and white. If it is necessary to unfold the
films, heat could be applied since they are all thermoplastic and
will reversibly soften. I suggest putting them in an oven at 35 deg.
C initially and increasing the temperature gradually if necessary.

Yvonne Shashoua
Senior Researcher
Dept. of Conservation
National Museum of Denmark
I.C. Modewegsvej-Brede
DK-2800 Kongens Lyngby
Denmark


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                  Conservation DistList Instance 22:35
                 Distributed: Monday, December 8, 2008
                       Message Id: cdl-22-35-010
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