Wednesday, October 7, 2009


A high-tech hunt for a lost Leonardo

Expert Uses Lasers, Neutrons To Uncover Da Vinci’s Largest Masterpiece, Hidden Inside A Wall

John Tierney

Florence, Italy: If you believe, as Maurizio Seracini does, that Leonardo da Vinci’s greatest painting is hidden inside a wall in Florence’s city hall, then there are two essential techniques for finding it.

First, concentrate on scientific gadgetry. After spotting what seemed to be a clue to Leonardo’s painting left by another 16th-century artist, Seracini led experts in mapping every millimeter of the wall with lasers, radar, ultraviolet light and infrared cameras. Once they identified the place, they developed devices to detect the painting by firing neutrons into the wall.

Seracini was standing in the Palazzo Vecchio’s grand ceremonial chamber, the Hall of 500, which was the center of Renaissance politics when Leonardo and Michelangelo were commissioned to adorn it with murals of Florentine military victories. In 2009, it remained the political hub, as evidenced by the sudden appearance of Florence’s new mayor Matteo Renzi.

The scientific lecture ceased as Seracini moved quickly to intercept the mayoral entourage. He was eager to use the second essential strategy for retrieving a Leonardo painting in Florence: find the right patron.

Seracini, an engineering professor at the University of California, San Diego, had spent years in bureaucratic limbo waiting to try his neutron-beam technique, but he saw this new mayor as his best hope yet.

The quest had begun more than three decades earlier. In 1975, after studying engineering in the US, Seracini returned to his native Florence and surveyed the Hall of 500. He was looking for “The Battle of Anghiari”, the largest painting Leonardo ever undertook (three times the width of “The Last Supper”). Although it was never completed, he left a central scene of clashing soldiers and horses that was hailed as an unprecedented study of anatomy and motion.

Then it vanished. During the remodeling of the hall in 1563, the architect and painter Giorgio Vasari covered the walls with frescoes of military victories by the Medicis.

But in 1975, when Seracini studied one of Vasari’s battle scenes, he noticed a tiny flag with “Cerca Trova”: essentially, seek and ye shall find. Was this Vasari’s signal that something was hidden underneath?

The technology of the 1970s did not provide much of an answer. In 2000 he returned to the hall with new technology.

The new analysis showed that the spot painted by Leonardo was right at the “Cerca Trova” clue. The even better news, obtained from radar scanning, was that Vasari had not plastered his work directly on top of Leonardo’s. He had erected new brick walls to hold his murals.

But how could anyone today know what lay behind the fresco and the bricks? Seracini was suggested to send beams of neutrons through the fresco.

One device can detect the neutrons that bounce back after colliding with hydrogen atoms, which abound in the organic materials (like linseed oil and resin) used by Leonardo. The other device can detect the gamma rays produced by collisions of neutrons with the atoms of different chemical elements. The goal is to locate the sulfur in Leonardo’s ground layer.

Developing this technology was difficult, but not as big a challenge as getting permission to use it. Once he gets permission, Seracini hopes to complete the analysis within a year. If he is right, then perhaps Vasari did Leonardo a favor by covering up the painting — and taking care to leave that cryptic little flag above the trove. NYT NEWS SERVICE