Bronze Bull

One of the artifacts that we were asked to treat (as a challenge) is
a broken bronze bull, estimated around 0 BC. This bull is filled
with kind of half burned clay. The bronze cover is very thin, 1 mm.
The only leg that was attached to it broke with a mere touch. It
looks like the cuprous chloride contaminated the inside and outside
of the bronze shell. There are some cracks, but no holes. The legs
were fitted with the aid of adapters placed inside and attached with
variety of epoxy glues.

A decision was made not to give the artifact a sesquicarbonate
treatment because it looks too dangerous. The aim is to give it a
minimal first aid treatment that will keep it "alive" and to leave
the original patina.

How can we treat the bronze disease at certain areas (we use zinc
dust treatment but with no clear effects)? We would like to do BTA
treatment. What kind of precaution is needed due to the small cracks
and the clay inside? Is there another alternative, like brushing
with BTA?

How can we give the patina a homogeneous look?

Mordi


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                  Conservation DistList Instance 21:35
                Distributed: Tuesday, December 18, 2007
                       Message Id: cdl-21-35-018
                                  ***