Prospects for the long term maintenance of outdoor bronze sculpture: The Shaw Memorial nine years after cleaning and coating

Clifford Craine, Kent Severson, and Scott Merritt

Abstract

A system of treatment and maintenance used by conservators for more than a decade is discussed and evaluated. A treatment performed nine years ago was recently re-treated. This and other treatments will be illustrated and discussed.

The Robert Shaw Gould Memorial, by Augustus Saint-Gaudens, is a bronze sculpture in very high relief set into an architectural surround designed by Charles F. McKim. It is located facing the State House in The Boston Common, and was dedicated in 1897. In 1982, after 85 years of exposure, the black copper sulfide and green copper sulfate streaked monument was cleaned by hand and repatinated. Missing elements were replaced, and the surfaces were coated with Incralac and wax. The sculpture was maintained annually by washing, retouching damaged Incralac and coating with Butcher’s Wax.

After nine years small pin holes appeared in the coating resulting in shallow pits of light green corrosion. It is thought that these pin holes correspond to small raised irregularities in the surface. When originally coated, these spots would have received a thinner coating of acrylic and wax. The thin coating, along with exposure to wear from man and the elements, could have led to breakdown of the coating in these areas.

Nine years of dirty wax was removed with mineral spirits. Since the old Incralac was perfectly soluble in both acetone and toluene, a new layer of Incralac was applied over the old to reform and renew the coating. A final coat of microcrystalline wax mixture was applied.

Eight bronze sculptures by John Massey Rhind situated at the Carnegie Institute in Pittsburgh were treated in a similar manner. However, the four sculptures atop the building, 85 feet above the street, were not coated with wax as it was decided that the wax would not be maintainable. Four years after treatment the sculptures were removed from the building as part of a roofing project. This provided an opportunity to inspect the sculptures and assess their present condition.

These and other treatments will be discussed in terms of their prospects for long term maintenance.