The first unusual spots have
appeared on the faces, legs and abdomen of the Riace Bronzes and
experts say that more frequent check-ups are needed to ward off
"cancer".
The two Greek bronzes of naked, bearded warriors from around
460-450 BC were found in the sea near Riace in 1972. They are
currently held at the Museo Nazionale della Magna Grecia in the
southern Italian city of Reggio Calabria, Italy.
Experts from the University of Salento and the Istituto
Superiore per la Conservazione e il Restauro (ISCR) in Rome made
the announcement at the National Archaeological Museum of Reggio
Calabria as part of the initiative 'Arte E(') Scienza', held
over the weekend in several Italian cities by the Associazione
Italiana di Archeometria (AIAr) to illustrate the most advanced
techniques of scientific investigations applied to culture.
One example is fluorescent X-rays, a non-invasive diagnostic
technique used by the "doctors" in charge of the bronzes to
examine them "lying down" in a sort of "field hospital" set up
in Palazzo della Regione Calabria.
Researchers were able to analyze the chemical composition of
the patina left on the lower part of the two statues and create
a sort of map of the spots which will serve to draw up future
"cancer prevention" strategies.
"On both of the bronzes," said Giovanni Buccolieri, applied
physics researcher at the University of Salento, "we found
several places that were covered in a blue patina created by
chloride residue left by the long period in the sea. Under
certain temperatures and humidity, these spots could spread with
the risk of forming a sort of 'bronze cancer', a corrosive
phenomenon that would damage the conservation of the statues."
To prevent this, the patina should be removed - similar to
what is done to birthmarks on patients at risk of melanoma.
Any intervention, however, would be somewhat invasive and
"thus for the moment", the researcher said, "we can just monitor
the evolution of the situation with more frequent check-ups."
The analyses brought to light two other surface patinas: a
reddish one created by the natural oxidation of copper contained
in the alloy, and a black multi-layered one that is compact and
smooth, made of copper sulfate.
"The latter was probably protective wrapping for the
statues," Buccolieri said. "The patina is still clearly visible
on Bronze A ('The Young Man'), while it has been partially
removed from Bronze B ('The Old Man') due to restoration done in
Florence in the 1970s."
The invasiveness of the intervention is also shown by the
zinc residue on the "skin" of the warrior, which "was probably
left by brass brushes used during the cleaning of the statue",
he added.
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