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.

In the past I worked on a few works of art composed of everyday
textiles painted in acrylics and then coated in polyester from a
similar time period and undergoing similar sounding decay. If I
remember correctly, the cause was the plasticiser migrating to the
surface, creating a soft sticky surface that easily attracted dirt
and picked up surface impressions of whatever pressed against it.

The surface could be swabbed clean of the excess plasticiser to
reduce the stickiness and surface softness. As solubilities can
change with the age and formulation of the plastic I suggest you do
small swab tests with different solvents to see what will remove the
surface stickiness without dissolving the plastic, or leaving it
cloudy and blushed.

Unfortunately, the process is the inherent vice of plastics. The
loss of plasticiser causes the plastic to shrink, develop cracks,
change texture, and/or become more brittle. The aging process of
plastics can not be stopped; however, it can be slowed by sealing
the object in an airtight, oxygen free, moisture controlled, light
impermeable container and put in a freezer (provided it is not the
kind of plastic that off-gasses nasty vapours such as chlorine or
nitric acid, in which case you need ventilation as well, but
polyester shouldn't cause such problems). This isn't very useful
when you want to display the object though.

Valerie Tomlinson
former conservator


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                  Conservation DistList Instance 20:19
                  Distributed: Monday, October 9, 2006
                       Message Id: cdl-20-19-001
                                  ***