Palazzo Pontificio, 1665-1669, by Giovanni Battista Falda (1643-1678). Engraving on handmade laid rag paper from Il nuovo teatro delle fabbriche et edificii in prospettiva di Roma moderna, sotto il felice pontificato di N.S. Papa Alessandro VII, published by Giovanni Giacomo De Rossi. Georgetown University Art Collection; Booth Family Center for Special Collections.
This engraving had severely discolored - to become almost brown - as a sign of chemical breakdown and advanced decay of the paper. In addition, a lining of a coarsely woven fabric had been applied long ago, likely and ironically in an effort to preserve the print. Many water stains also damaged the print’s surface, including one stain that measured approximately four inches in length. And added to the overall soiling on the print’s surface were a vast number of droppings left behind by insects. Conservators surfaced cleaned the engraving and carefully washed it to remove the fabric lining and to reduce the acid that had built up chemically in the paper over time. In addition, the engraving was gently flattened, with conservators taking extra care to preserve the plate mark left behind as part of the printing process.