Polyester resins

Simon Moore <simon.moore [at] hants__gov__uk> writes

>... Does anyone know of a panacea that I can spray onto
>lepidopteran wings which will not mask their markings or
>iridescence but will prevent them from clearing in the resin.  I am
>presently not using any other types of resin as I have found that
>some have longer-term surface pitting problems.

So far I have tried: spray deodorant, polished surface matting spray
(used in photography), 5% PVA in ethanol, acrylic varnish and hair
lacquer.  All of these have failed--mainly due to solvency in the
styrene. Does anyone know of a panacea that I can spray onto
lepidopteran wings which will not mask their markings or iridescence
but will prevent them from clearing in the resin.  I am presently
not using any other types of resin as I have found that some have
longer-term surface pitting problems.

My own quick experiments with an old butterfly I had were failures.

I think you would have to completely prevent contact with the resin
and I don't know that this is possible, especially for a spray
coating.  I wonder if an airspace can be provided somehow so that
the specimen is trapped and protected, but not immersed?  For
instance, cast a two-part block with a butterfly-shaped depression
in one of them, insert the butterfly and then weld the two halves
together.  This won't preserve it as well, but won't interfere with
the optical properties.  Of course this is a far more time-consuming
task.

Perhaps a cellulose ether consolidant like like CMC in water or
hydroxypropyl cellulose in ethanol might not change the optics of
the wing, or be affected by the resin.  Another off the wall
suggestion (that probably won't work!): spray starch.

If preservation is the aim, these substances might enhance
deterioration and are utterly irreversible on such a fragile
specimen.  If display is the aim, perhaps standard pin-mounting in
clear boxes is better.  But if they must be handled frequently, I
suggest some sort of entrapment procedure like above.

You mentioned surface pitting of resins.  This may be caused by
incomplete mixing of the resin.  As I am sure you know it is
important that all monomers/accelerators (including those adhering
to sides of containers, on stirring sticks etc) be fully
incorporated into the mix, as residuals could interfere with proper
setting and definitely cause problems later. Sometimes decanting the
mixed resin into a new container and stirring a second time with a
clean rod will assure complete blending.

Linda S. Roundhill
Art and Antiquities Conservation
18121 157th Ave NE
Woodinville WA 98072
USA


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                  Conservation DistList Instance 18:27
                Distributed: Thursday, December 16, 2004
                       Message Id: cdl-18-27-002
                                  ***