Page 14 - Copper and Bronze in Art: Corrosion, Colorants, Getty Museum Conservation, By David Scott

Gilding and the use of gold coatings over copper is another important topic, although it is
usually considered from the point of view of the gold, rather than the substrate. This subject is
not considered in depth here, since a detailed review of the subject of gilded surfaces on metal
has recently been published (Drayman-Weisser 2000).
There is a romance to bronze in that it can be used so readily for both ornamental and utili­
tarian purposes. It can assume many aeruginous forms, from the meretricious yellow imitation
of gold to the black of jet, from the pale green of olives to the lustrous gray green of the sea. It
can have a surface as reflective as silver or as red as the color of cinnabar, varying in luster from
subfusc to erythemic to golden or salmon pink. Unlike bronze, gold does not alter, nor does iron
gain an attractive patina. No other alloy possesses so many attributes: bronze is the sono­
rous bell metal, the delicate rail of a curving stair, the grace of a Bronze Age youth, the weighty
silence of a polished Buddha, the untold history of an encrusted sword blade; bronze is a sym­
bol of strength and beauty from ax blade to breastplate.
Bronze, which is principally made of copper, is also one of the few metals we are prepared
to admire covered completely with corrosion products; many observers even preferring the
appearance of a patinated surface, whatever the hue, to the original color of the metal. As it cor­
rodes, bronze becomes evidence of time past and time passing, and we value it for the authen­
ticity of its interaction with oxygen, water, carbon dioxide, and soil. The variety of minerals that
can form on bronze over time is enormous, the subdeties infinite. Whether deliberately pati­
nated or polished, corroded or cleaned, bronze possesses an allure that comes from its longev­
ity and its appeal to so many different tastes and fashions. It will oudive us all and will still be
admired by generations to come, just as bronzes created many hundreds or even thousands of
years ago continue to be admired today.
The inspiration for this book was a 1963 article by Rutherford J. Gettens for the Smith­
sonian Institution in which the author reviewed the state of knowledge at the time in regard to
metallic corrosion products on antiquities (Gettens 1963a). As of this writing, thirty-seven years
have passed since Gettens's work was published, and our knowledge of the subject has expanded
considerably, yet much remains for future investigation. Now, at the beginning of the twenty-
first century, we can look back at the distribution of publications that were used in writing this
review of the literature and begin to see some trends. As shown in FIGURE 1, a noticeable rise
in the number of publications on the subject of copper conservation begins around the 186OS,
I
then decreases shordy before World War . After some recovery during the 1920s and 1930s,
the number of useful publications declines precipitously with the advent of World War I.
I
The establishment and development of the conservation profession in the aftermath of that war
is revealed by an exponential increase in the number of publications from the 1950s to the 1980s.
This rise may now be leveling off, however, as indicated by the fact that about 170 publications
cited in this book date from 1980 to 1990 and about the same number from 1990 to 1999, the year
in which this review of the literature was completed.

P R E F A C E
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