Page 349 - Copper and Bronze in Art: Corrosion, Colorants, Getty Museum Conservation, By David Scott

(1525-1608), exhibits a darker patinated finish. This sculpture, also at the J. Paul Getty Museum,
is shown in PLATE 70. For most of these Renaissance sculptures, a green patina would be unnec­
essarily crude since it would usually be opaque, hiding the nuances of the surface metal.

Unraveling an object's The intricacies surrounding the issue of surface appearance are
patination history exemplified by Nessus and Dejanira, a Renaissance bronze attrib­
uted to Giambologna (act. ca. i69o) in the collections of the
Huntington Library and Art Galleries in San Marino, California. There are three known signed
versions of this bronze group; the other two are in the collections of the Louvre in Paris and
in the Skulpturensammlung in Dresden (Bewer 1996). The surface patina of the bronze is
very uneven, and some parts appear to have been repatinated. The surface scratches may have
a number of different causes. In some areas, friable white deposits suggest that a plaster piece-
mold may have been taken from the bronze at some stage. In addition a series of deep, straight,
darkened scratches run in one line from the figure's right shoulder, across the body, and down
the left side, resembling the marks often made during the process of surmoulage (taking a
plaster mold directly from a finished bronze). The marks from a plaster piece-mold should be
positive, so perhaps the surface scratches in the metal are a result of taking a gelatin mold from
the sculpture. 15
A bronze pin had been used to repair a break in a leg, and solder had been used to secure
the repair. This was replaced in the modern restoration of the piece with a stainless-steel pin and
epoxy resin. The bronze has been finished with a fine scratch-brushed surface that shines
through the primary translucent layer.
An interesting attempt to discover more about the way Giambologna finished his bronze
surfaces was investigated by Stone, White, and Indictor (1990). They found that various oils,
pitches, and resins had been used to coat the surfaces of the sculptor's bronzes in the collections
of the Metropolitan Museum of Art. In recessed areas, the reddish brown coating has darkened
and become opaque; in some exposed areas, the coating is worn away and the metallic surface
appears gray. Another coating of a different material covers selected areas of the lacquered
figures. In Nessus and Dejanira, for example, Nessus's face is covered by a fine layer of darker
opaque, grayish green, brittle material with granular inclusions; this appears to be a hard waxy
solid. A deeper red, lacquerlike coating covers most of Dejanira and has flaked off in some spots,
revealing the wire-brushed metal surface below. Under ultraviolet illumination, the thicker
deposits show a bright yellow-green fluorescence, which is suggestive of shellac. The surface
patina of this bronze therefore reflects a complex pastiche of events that could have occurred at
any stage from the sixteenth to the nineteenth century. It is difficult to be sure of the nature of
the original finish applied to such Renaissance bronzes, although in this case it can be inferred
that the wire-brushed finish was specifically employed to enable the subtle surface reflections to
show through a translucent reddish brown surface coating.

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