New look presidents
August 1st 2005 Kärcher, the German cleaning equipment manufacturer, is cooperating with the National Park Service to clean the presidents’ heads on Mount Rushmore in South Dakota (USA). The restorative cleaning work will be carried out as part of a culture-sponsoring project.
The aim is to remove lichen, algae, moss and other organic stains that could damage the underlying rock in the long term by way of biocorrosion.
Cleaning is to be performed purely with water, without any chemical supplements. Five dieselpowered Kärcher HDS 1000 DE hot water pressure washers will spray the water on to the granite surfaces via rotary nozzles that combine the cleaning power of a pencil jet with the higher area coverage of a fanjet.
Water temperatures around boiling point will delay any recurrence of growth on the rock sculptures.
Following cleaning trials at the end of April, two independent scientific expertise deemed this process to be the most effective and most gentle on the material.
Sculptor Gutzon Borglum’s giant heads of American Presidents George Washington, Thomas Jefferson, Theodore Roosevelt and Abraham Lincoln were carved between 1927 and 1941. They are about 60 ft (18-meters) high and, along with the Statue of Liberty in New York, probably the best known monument in the United States. More articles from Karcher (UK) Ltd: | 
