The Richard H. Driehaus Museum in Chicago
Coal burning in the 19th century led to the accumulation of black soot, which caused erosion of the decorative stone elements. In order to prevent further damage to the sandstone, those responsible decided to remove the soot incrustation.
During the testing of numerous methods it turned out that Clean-Lasersysteme GmbH from Germany has the most efficient and gentle method for removing the stubborn soot and soil deposits. At that time the cleanLASER was cleaning with an average speed of about 2.5 m² per hour. After 18 months the museum was restored to its original condition. For the first time this laser cleaning method was used to restore the outside of an entire building in the United States.
The original patina, veining and and coloration of the stone were preserved by laser cleaning. The removal of the soot incrustation enables the natural oxidation of the stone. Since the completion of the laser cleaning, the stone has proven to darken somewhat overtime, providing an age appropriate aesthetic.
The exterior walls of the “Nickerson Mansion”, as the museum is also known, which have been tested under harsh winters, are still in top condition 16 years after the laser restoration.
In the meantime, cleanLASER has further developed the systems and offers even more efficient laser devices for restoration today.
https://driehausmuseum.org/about/restoration