Exhibition showcases conservation technology behind terra cotta preservation

A new exhibition in the Christian Petersen Art Museum, Morrill Hall, showcases the innovative technology and conservation science used to preserve Danish American artist Christian Petersen's iconic terra cotta sculptures across campus. "Terra Cotta Conservation in the Art on Campus Collection," which opens Monday, Jan. 12, prior to the start of spring semester, features materials samples, 3D scanning documentation and behind-the-scenes insights from the ongoing conservation of the History of Dairying fountain in the courtyard of the Food Sciences Building. The 1934 sculpture is a National Register of Historic Places landmark and one of the nation's earliest Public Works of Art Project (PWAP) installations.

Democratic material meets Iowa weather

Working within Depression-era constraints, Iowa State College President Raymond Hughes (1927-36) directed Petersen to work in terra cotta -- "perhaps in tile or pottery" -- because the ceramic engineering department could produce it on campus within the tight PWAP budget and timeline. The material was affordable and expressive, and Petersen could create detailed public art for Iowa State's students at a fraction of the cost of bronze or marble -- which aligned with the land-grant mission of serving everyone, not elite institutions. The hand-modeling technique allowed him to capture intricate details in works like the Fountain of the Four Seasons (1941) on the north lawn of the Memorial Union, and Three Athletes (1936) on the front of the north exterior staircase of State Gymnasium.

However, the terra cotta sculptures face challenges from human acts exacerbated by Iowa's freeze-thaw cycles. The same material that once drained Iowa's agricultural fields as drain tiles graces campus buildings and public spaces, requiring specialized preservation approaches developed through ISU's materials science and engineering expertise.

"What we're addressing with Petersen's sculptures are primarily well-intentioned human interventions over the decades -- maintenance decisions or installation techniques -- that created vulnerabilities which Iowa weather then exploits. This is why routine, professional care matters so much for public art and our cultural history," said Lynette Pohlman, the Warren and Beverly Madden Endowed Director and chief curator of University Museums.

"Often the deterioration begins with a human act, for example, sandblasting the glazed surface, not maintaining the grout, putting tar over the terra cotta that holds in moisture, reinstalling improperly or not allowing an air/water space behind the terra cotta panels, even vandalism that breaks the terra cotta," she added. "These terra cotta repairs have all been associated with Christian Petersen's public art installations and are the base cause for conservation."

Innovation in action

The exhibition highlights the partnership between University Museums and manufacturing and teaching labs in the College of Engineering, where teaching lab specialist Sawyer Krotz conducted comprehensive 3D scans of the History of Dairying fountain to create precise digital models for replication. The same technology was used to replicate the terra cotta for the Fountain of the Four Seasons, rededicated last summer after a multi-year conservation. 

"Prior to 3D scanning, successive replications of sculptures would be smaller than their originals due to approximately 5% shrinkage when terra cotta is fired," said Sydney Marshall, curator at university museums. "A direct mold of the original would ultimately produce a smaller result because of that shrinkage. With 3D scanning, we can digitally scale up the models by 5% before creating the molds, ensuring the final fired terra cotta matches Petersen's original dimensions exactly."

After 3D scanning, the digital models are used to create forms that terra cotta specialists use for traditional slip-casting methods. The active History of Dairying conservation project, which will include foundation repairs, mural preservation and tier replication, is underway, with fundraising still in progress to complete this preservation effort.