Controversy over proposed repainting of a portion of the former US Patent Office Building in Washington, DC, stimulated technical and ethical questions about painting stone. The oldest part of the building was constructed with tan-colored Aquia Creek sandstone facing, and its surface was painted white only when the next section of the building was faced with marble. The paint has deteriorated over the years, and its last remnants were removed in 1968 when the building was renovated to become the dual seat of the Smithsonian Institution’s National Collection of Fine Arts and National Portrait Gallery. As part of further rehabilitation in 2000, the consulting architects proposed painting the sandstone again, but after considerable discussion it has been decided not to repaint for the moment. Issues to be considered in making such an important decision are discussed.