Cleaning and Repointing the 1910 Building

Buildings get dirty! On the National Mall, open every day, and surrounded by mature plantings, this historic building demanded a special cleaning strategy.

After extensive investigations and sample testing, we selected an environmentally friendly baking soda system. Although it did a great job of cleaning the granite, the baking soda proved impossible to contain.  People complained about white powder on their cars and Smithsonian horticulturalists complained about it on the specimen trees. Back to the drawing board, but with the contractor on site we had to make quick decisions.

In consultation with the Smithsonian, we chose the classically gentlest means possible: diluted stone cleaning solutions and careful hand brushing. For heavy soiling, rust stains, asphaltic goop, and bird droppings, we tested then specified an array of scrubbing, scraping, and chemical cleaners.