Walk in to the Louvre, take a flash photo of the Mona Lisa and chances are you’ll be promptly escorted out by some rather unhappy security guards. Besides obvious copyright and security concerns, museum curators take a dim view of light from flashbulbs hitting the priceless art works for which they’re responsible.
So Roman Maev and Dmitry Gavrilov weren’t surprised when their suggestion to blast paintings with an intense pulse of light as part of a method to determine their condition and authenticity was met with some initial resistance.
“They thought we were crazy,” admits Dr. Maev, a University of Windsor physicist and director of the Institute for Diagnostic Imaging Research.
Thermography, however, is gradually being embraced as a method of both authenticating works of art and helping curators better understand what’s required to preserve them, and Maev and Gavrilov, a PhD student in his lab, are paving the way for its acceptance.
A method of non-destructive evaluation, thermography can be used to analyze the properties, structure and condition of a painting by studying its temperature dynamics. In various other forms, it’s used for everything from medical diagnostic imaging to thermal mapping for detecting heat loss in buildings.
For Maev and Gavrilov’s purposes, it involves sending a rapid pulse of light with an optical flash which slightly raises the surface temperature of their subject. A thermal camera takes a series of snapshots, capturing the temperature at each interval. The pattern of how the surface cools reveals what’s underneath. The process can detect defects, various weave patterns in canvas, and in some cases, reveal alterations that may have been made to a painting over time.
Besides better understanding levels of degradation, it may also help experts reveal forgeries, which according to the FBI, is a $6 billion per year trade, making it the third most lucrative crime in the world after drug trafficking and the illegal weapons trade, Maev said.
Naturally, museum curators were apprehensive when told how the process works, but in fact, exposure may be hundreds of times less than the regular light a painting is exposed to during the course of a day, according to an article they recently published in the Canadian Journal of Physics.
“Touching the painting with your finger actually raises the temperature of the painting more than this process does,” said Gavrilov.
So far, they’ve used the process at the Fitzwilliam Museum at the University of Cambridge and in Moscow at the Pushkin State Museum of Fine Arts. In Cambridge, they analyzed a series of seven paintings called Triumph of the Eucharist by P.P. Rubens. Their goal was to determine whether the individual panels were painted on separate wood plates, or if they were painted on one large panel that was cut into pieces after the fact. Their analysis revealed that three of the panels had similar wood grain structure, while other panels had entirely different wood grain.
The team has also been invited to the National Gallery of London to work on a collaborative international Rembrandt project this summer.
Thermography, however, isn’t the only high-tech process used by the team, which also includes Darryl Almond, a professor at the University of Bath. Infrared imaging, spectroscopy, UV fluorescence analysis, and acoustic microscopy are among the other innovative techniques they use to conduct pre-restoration analysis of works of art, and all are described in their article.
“It’s breakthrough technology,” said Maev. “As physicists, this is fascinating for us.”