But can FingArtPrint work on all the objects that a museum might collect–or that a smuggler might sneak through customs? Last fall, Wei and his team arranged a set of case studies for 30 objects from various museums and galleries, including an Egyptian stone medallion, a Roman glass bottle, books, an oil painting, several cast-bronze sculptures, and a wooden mask. Most of the objects lent themselves to fingerprinting with this technique. Brush strokes, the crackling of varnish, a layer of printed ink, the pattern of rust, and other irregularities in the surface of wood and ceramic–the profilometer generated unique patterns for all. Even two bronze sculptures taken from the same mold generated two distinct roughness profiles.
One potential limitation of the fingerprinting technique is how natural rates of change might alter the fingerprint itself. “What happens as a painting ages, and the microstructure changes: will changes due to aging then look like a forgery?” asks Hany Farid, a computer scientist at Dartmouth University who specializes in imaging.
The researchers own evaluation found that the process doesn’t work well with textiles and objects that decay rapidly. But it could still be useful for a wide variety of other items.
Currently, owners try to keep track of fine works of art by photographing the entire object or by marking it or attaching a tag or sticker to it. But photographs can be forged, engravings alter the surface, and adhesives and inks might disrupt the delicate chemistry of old objects. “Whenever you have an intervention to an object–say, to put a serial number on it–you want it to be reversible,” says Little. “But it’s complicated to make something reversible and yet permanent at the same time.”
Research into fingerprint durability is ongoing, says FingArtPrint’s Wei. He adds that fragments of fingerprints can be as valuable in art identification as they are in detective work. Other changes, such as the yellowing of a varnish, could be calculated into the fingerprint information.
Wei says the first FingArtPrint prototype should be completed this year.