Resin for bronze

David Cottier-Angeli <dca [at] cottiermetal__ch> writes

>The major problem we are facing is the migration of copper ions into
>the amine/epoxies and anhydride/polyurethane ...
>...
>The resin has to support small freshly excavated archaeological
>copper fragments that are chemically quite reactive. ...
>soft and rubbery and capable of gently gripping the fragment. And it
>also has to be chemically stable over a period of several years. But
>we are primarily interested in a material that is soft and perhaps
>slightly tacky.

The posting deserve the following comments:

You have to take some preventive measures, these fragments coming
from an archaeological excavation need first of all a removal of
CuCl from the corrosion layer, eventually fixing any flaking of the
carbonate layer and stabilization of the copper by a corrosion
inhibitor. And only then you can proceed to look for the synthetic
support.

I would suggest as a temporary solution, that may help to have an
idea on the original artifact that produced these bronze fragments;
is to try to fix them on a "Mylar" sheet using either methyl
cellulose or Agar-Agar that one can adjust their viscosity. These
gels are water based, totally reversible, they are not harmful when
contact with chloride free bronzes is not too long.

Slim Khosrof
INP-Conservation Lab


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                  Conservation DistList Instance 24:12
                 Distributed: Tuesday, August 10, 2010
                       Message Id: cdl-24-12-003
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