Page 373 - Copper and Bronze in Art: Corrosion, Colorants, Getty Museum Conservation, By David Scott

recommended a treatment developed by the French restorer Alfred André that began with thor­
oughly drying the bronze, excavating the actively corroding region with a needle, and then seal­
ing the canker with a drop of Palestine bitumen. Either of these treatments would have been
i
efficacious f conscientiously employed. Potassium hydroxide pellets are an effective desiccant
in wide laboratory use over the past one hundred years. The drying, excavating, and sealing
of actively corroding areas are not very different from a number of more recent conserva­
tion treatments.
Lack of intervention has not been particularly harmful to the average bronze artifact. The
collections of the National Museum of the American Indian are a case in point. Very few of the
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bronzes in this collection, which date from around 1900, have been treated at all. Those few arti­
facts that were treated at some unknown time in the past were stripped, resulting in the usual
loss of surface information. Those treated only to benign neglect retain the dusty ambience of
bronzes that have remained undisturbed by storage in an essentially uncontrolled environment
for nearly one hundred years, with their original patinas intact.

Other early Various approaches to chemical or mechanical cleaning have
treatment methods been tried on a wide array of bronzes from different contexts.
An interesting and quite laudable early approach to the cleaning
of marine finds is that of Zenghelis (1930), who treated such important large bronze sculptures
as the Ephebe of Marathon and a Zeus recovered from Cape Artemision, Greece. Zenghelis first
soaked these bronzes for several months in frequent changes of distilled water to remove salts,
then softened the remaining deposits with superheated steam before removing them with local
mechanical cleaning. None of these treatments would have necessarily entailed drastic alter­
ation to the patina or the appearance of the bronze.
The methods used by commercial dealers to clean and patínate bronzes today often have
their roots in traditional practice, involving a number of esoteric or mundane substances that
range from secret concoctions to materials as prosaic as oven cleaner or lemon juice. Both strong
lye and citric acid are traditional methods with long pedigrees. One dealer surveyed in Los
Angeles usually begins treatment by spraying the entire bronze with an aerosol can of oven
cleaner, followed by a thorough washing in water. The bronze is next heated with a blowtorch
until hot to the touch and then sprayed with a commercial wax, such as Pledge, followed by
buffing and polishing. Although this treatment is not as harmful as those that rely on soaking in
acids or on reducing the corrosion products electrolytically, the oven cleaner usually contains
sodium hydroxide that will remove or alter patina constituents along with any attendant dirt or
encrustations. The local application of heat to a small bronze object can also be damaging and,
in some cases, very destructive.

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