Outdoor bronze sculpture

During restoration works on an equestrian outdoor bronze sculpture
was found, inside the structure (localized in the proximity of
horse's knees) a mass of yellow sulphur. In these areas is also
localized a phenomenon of corrosion with the presence of wet
chalcantite (CuSO4 5H2O).

I would like to know if the presence of sulphur inside metallic
structures, such as outdoor statues, has already been found on other
occasions, and how. What was the function of sulphur itself? Was it
applied at the moment of making the fusion of the bronze? Was it was
added during restoration work?

The great corrosion process can be due and activated by the presence
of sulphur?

I'll be grateful to anyone could help me by sending any information
or any bibliographic references about these issues.

Dr. Paola Croveri
Department of Inorganic, Physics and Materials Chemistry
University of Torino
Via P. Giuria 7
10125 Torino, Italy
+39 011 6707554
Fax: +39 011 6707855


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                  Conservation DistList Instance 19:15
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