Polyester resin objects

Meghan Mackey <mtmackey [at] tds__net> writes

>I am looking for input from anyone with experience working with cast
>polyester resin objects, especially tacky (as in sticky) polyester
>resin.
>
>An installation of over 200 cast polyester resin books made between
>1975 and 2003 is being cleaned and readied for installation. Many of
>the books have tacky surfaces.  This has caused dust and grime to
>adhere to the books.  In addition, a pattern has been left on the
>surface by a Tyvek and bubble wrap used to wrap the individual books
>for shipment.  In addition, fragments of the cast objects have
>broken off and need to be joined.

Reading your description of some of the objects having tacky
surfaces, I wonder whether this is because the polyester is breaking
down--I have experienced this also with epoxies and it is caused by
either an uneven distribution / mixing of the two components during
manufacture, or caused by inaccurate measuring of quantities of
hardener and resin. The product is then unstable and prone to
'weeping' surfaces, or results in a sticky surface. This may take
only a few months to manifest itself or a number of years and is
influenced by temperature, light and RH, but also by the type of
product used. Some are more stable than others.

There is nothing you can do about this unfortunately as far as I
know.

Acrylic adhesives are all fine for re-gluing broken off pieces of
polyester resin.

Detlef Klein
Conservator
Manawatu Museum Services Ltd
349 Forest Hill Road
Aokautere
Palmerston North
New Zealand
+61 6 3540703


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                  Conservation DistList Instance 20:17
               Distributed: Thursday, September 28, 2006
                       Message Id: cdl-20-17-001
                                  ***