Park Service using lasers to remove Jefferson Memorial’s grimy coating

The National Park Service is testing a high-tech treatment using lasers to remove a grimy, black film that has plagued the Jefferson Memorial for years. The park service contracted with a Chicago-based company to test its laser-ablation treatment on a portion of the monument in an attempt to remove the filthy-looking coating, known as biofilm. The grime — a colony of microscopic organisms that sticks to stone surfaces — first began appearing in 2006 and has grown more noticeable in recent years, particularly on the monument’s roof, park service spokesman Mike Litterst told WTOP. Starting next week, the Conservation of Sculpture and Objects Studio, Inc. will perform a test of its laser-ablation treatment on about 1,000 square feet on the northeast side of the memorial...more