Conservation of Public Sculpture

Andrzej Dajnowski at work
Photograph courtesy of Dajnowski

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Objects conservator Andrzej Dajnowski specializes in preserving and repairing public sculptures, outdoor monuments, historical artifacts, and art objects. After training and working in Poland, he received a master’s degree from the Center for Conservation and Technical Studies at Harvard University Fogg Art Museum, and has a background in chemistry and physics, art history, and fine-arts sculpting, carving, and painting. Dajnowski has published in the field of conservation and materials testing.

One of the serious problems facing outdoor, public sculpture is graffiti. The most expedient way to remove graffiti paint is with the application of baking soda or high-power sand blasting, but both of these methods are more damaging than they are restorative because they remove the surface of the stone along with the paint. To remove graffiti markings safely and effectively, Dajnowski uses steam, which draws paint out while leaving the surface of the material in tact. After steam cleaning the surface, Dajnowski applies a protective coating to the sculpture or monument to prevent any future graffiti from penetrating too deeply into the stone.

One of Dajnowski's most successful conservation projects was Loredo Taft’s Fountain of Time (c. 1920), located in Hyde Park, Illinois. The surface of this concrete fountain had become badly damaged through contact with water, weather, and periodic sand blasting. One problem was that organic growth had begun on the surface of the concrete, the normal pH of which had changed from an alkaline 14 to something closer to neutral 7. (Organic growth cannot occur in seriously alkaline or acidic solutions.) The decomposition of calcium—an important component in concrete—was also a concern because substantial losses began to develop across the surface, revealing the iron rebar used to support the sculpture. Rebar is typically used in concrete construction because it resists corrosion in an alkaline environment. Here, the revealed rebar began to corrode when the pH of the concrete fell below 10. When iron corrodes, it may expand as much as 10 times its original volume. In the fountain, the expansion of the inner support created pressure and eventual cracking in the surface material.

In order to repair these structural damages on the fountain, Dajnowski and his team measured the cracks in the fountain to see if they expanded or contracted, performed boroscopic studies, and took temperature and humidity readings. Then, based on their new knowledge, the team created a new aggregate concrete to fill cracks and resurface sculptural features. The new concrete was designed to resist binding to the original concrete so that new stress would not be put upon the structure. Some supporting rebar was replaced with titanium dowels, which expand and contract at the same rate as concrete. Although still unfinished, the repairs that have been made to the fountain are functioning as Dajnowski predicted: The structural flaws have been stablized. Moreover, the aesthetic beauty of Taft’s original vision has returned to this work of art.