The Thomas Jefferson Memorial is slated for a cleaner look after the National Park Service recently concluded a successful test using laser ablation as a means of removing biofilm that cause the memorial's dome to darken.
“We’re very satisfied with the results of this laser ablation test,” Architectural Conservator Justine Bello told the National Mall and Memorial Parks website. “The level of clean that was achieved exceeded our expectations. We were able to clean the stone in a safe manner that protected both this cultural resource and the surrounding natural environment.”
With the cleaning taking place over the last month, the test treatment cleaned approximately a tenth of the 10,682 square feet that comprise the dome. The results will be visible as the scaffolding is removed from the Jefferson Memorial dome over the next week.
Going forward, the plan calls for authorities to remove the remainder of the biofilm concurrently with a project to rehabilitate the memorial's roofs. The blackening effect of biofilm, a colony of microscopic organisms that adheres to stone surfaces, became apparent in the memorial’s white marble in 2006 and has become more pronounced in recent years.
To determine the best treatment options, a multi-disciplinary team of conservators, architects and other professionals have studied the growth on the Jefferson Memorial over the last seven years.
The dome’s ablation test was conducted by Chicago-based conservation firm, Conservation of Sculpture and Objects Studio, Inc.
