life-span of the coating ranges from 7 to 10 years if the sculpture is well maintained , and can be renewed by the application of additional coating material several times before having to remove the coatings and start the process over again . Keeping up with maintenance is cost effective in the long run and will ensure that the bronze looks good year after year . Landscape design and maintenance can also play an important role in preventive preservation by incorporating nonacidic elements into the design , and by cutting back existing overhanging trees and creating appropriate barriers between horticultural elements and the memorial .
Bronze objects are often accompanied by stone which can range from a simple granite pedestal to large scale decorative structures made from calcareous stone such as marble and limestone . In some cases the treatment of the stone can be more time consuming and complex than the work on the bronze object that it was designed to support ( treatment of stone memorials can be a topic for another article ). In many instances , we find that the areas adjacent to the stone pedestals or plinths have been modified . This includes regrading , which often covers important elements of the structure as well as excess plantings which surround the object ’ s site . Restoring the area around the pedestals to its original configuration and detailing often enhances the look of the memorial . In most cases , when the conditions warrant we prefer to treat the stone elements prior to treating the bronze .
As exemplified in the projects just described , restoring a memorial in a common , park or town square can be a vital first step in engaging the public to be more supportive of other improvements needed to cultivate beautiful open spaces .
Josh Craine is a Principal and Senior Conservator at Daedalus , Inc ., an art conservation company which specializes in the treatment of sculpture , monuments , fi ne art and architectural elements .
The basic steps for treatment of a historic bronze object are as follows ( these steps assume no recent treatment has been performed ):
Research : We try to find as many primary sources as we can which describe the sculpture or memorial ; these can include dedication booklets , images , newspaper stories and correspondence between the artist and patrons . Many times we can use these to pin point a desired surface color and find out what a missing part originally looked like .
Removal of loose-powdery corrosion products on the surface of the bronze : We prefer to use water blasting at about 3,000 psi . However , this can be done using other means as well . These include , but are not limited to ; abrasive blasting with a soft medium such as walnut shells , laser cleaning using Nd : Yag laser , or mechanically using extra fine abrasive pads . The goal of this phase is not bring the sculpture to bare metal . The goal is remove the corrosion products that are active on the surface .
Repair as needed : This includes making and casting missing parts from bronze , filling pinholes and cracks in the surface using specialized fillers and epoxies , removing ferrous repairs or chaplets and replacing them with bronze . If the bronze is unstable we remove it from the base and fabricate a new mounting system .
Re-patinate : We apply a surface color to the bronze using traditional patination techniques , using patina chemicals applied to a surface heated by a propylene fueled torch . This is not always an exact science and we test numerous patina recipes before we come to the desired color . We base the color on the research conducted earlier in the process .
Application of a surface coating : We prefer to use an acrylic coating ( Incralac ). It is applied in several layers ; the first by brush and the subsequent coats by spray . This is followed by a coat of paste wax that acts as a sacrificial top coat .
Boston Society of Landscape Architects Fieldbook
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