Iron Truss Conservation—Arts and Industries Building of the Smithsonian Institution
The Arts and Industries Building of the Smithsonian Institution, the second oldest building on the National Mall, underwent major renovations and maintenance beginning in 2004. The building’s roof was replaced as part of this maintenance. A fragment of the original iron roof truss and three accompanying architectural elements were salvaged and sent to us for treatment.
Paint was carefully removed from the surface of these elements using a chemical solvent-based stripper with nylon brushes and pads. Active corrosion uncovered when the paint was removed was stabilized by application of a tannic acid-based corrosion converter which reacted with active corrosion products to produce stable iron tannates. Finally, a coat of microcrystalline hot wax was applied to protect the surface of each element.