ROME - Analyzing 500-year-old bricks, engineers in California are searching for a lost Leonardo da Vinci fresco that some researchers believe is behind a wall in Florence's Palazzo Vecchio.
The hunt for the "Battle of Anghiari," an unfinished mural by Leonardo, has captivated art historians for centuries and is now being tackled by experts wielding state-of-the art scientific tools.
Laser scanners, thermal imaging, radar and neutrons will be employed in the project that Culture Minister Francesco Rutelli said is expected to take about a year.
Art lovers want to get to the bottom of the mystery in the Salone del Cinquecento (Hall of the 1500s) in the Palazzo Vecchio, a fortress-like palace in the heart of Florence that now houses municipal offices.
Maurizio Seracini, an Italian engineer, said he and colleagues at the University of San Diego are studying bricks and stonework that were found in a storeroom in the Palazzo Vecchio and were once part of the huge hall. The bricks were hauled to California, where their structure and composition are being analyzed, Seracini said by telephone.
Some researchers believe a cavity in one of the hall's walls might have preserved the mural, which Leonardo began in 1505 to commemorate the 15th-century Florentine victory over Milan at Anghiari, a medieval Tuscan town. The work was unfinished when Leonardo left Florence in 1506.
The search for the masterpiece was given new impetus about 30 years ago, when Seracini noticed a cryptic message on a fresco in the hall by Giorgio Vasari, a 16th-century artist famed for chronicling Renaissance artists' labors.
"Cerca, trova" -- "seek and you shall find" -- said the words on a tiny green flag in the "Battle of Marciano in the Chiana Valley." Since Vasari respected the Renaissance masters, some hypothesize he wouldn't have destroyed Leonardo's work on what is presumed to have been a wall behind one Vasari painted when he decorated the room in the 1560s.
A few years ago, using radar and X-ray scans, Seracini and his team found a cavity behind Vasari's fresco that could indicate a space between two walls.
"We're going to see if Vasari, instead of destroying, saved" Leonardo's fresco, Rutelli said Monday.
Next month, engineers using a laser scanner will start work on constructing a three-dimensional model of Vasari's wall, Seracini said. Chemical analyses of Vasari's paint pigments will follow, as well as thermal imaging to help better understand the wall structure.
By knowing the exact composition of the paint on the Vasari fresco and the wall itself, experts will have a better chance at understanding what might be behind it, Seracini said, when the next step comes -- sending a flux of neutrons through the entire structure.
"When we know what (Vasari's) pigments and wall are (made of), we can `subtract'" that information from the overall neutron analysis to establish the composition of the wall Leonardo worked on, Seracini said. "Leonardo's mural should be located on top of the original stone wall" of the hall. He said researchers know which pigments Leonardo used.
And if there's no Leonardo masterpiece behind Vasari's wall?
Seracini predicted that art restoration would benefit in any case since the project would pioneer ways for restorers to understand countless paintings that have been covered by whitewash and plaster.
The project is "absolutely a novelty in application" to the art world, Seracini said, adding that many of the techniques to be used in the Leonardo hunt are already employed in medical and military fields.
