X-rays reveal Leonardo's secrets in the Mona Lisa

A pioneering study shows that the master composed the faces using up to 30 layers of translucent paint

JULY 17, 2010.- X-rays have just revealed a new secret of the Mona Lisa and six other masterpieces by Leonardo da Vinci (1452-1519). For the first time since they were painted, a group of researchers, including a Spaniard, have been able to penetrate the different layers of paint that give Leonardo's faces a unique stamp in the history of art. They have achieved this thanks to the X-ray light that passes through to the bottom of the canvas without causing the slightest damage to the oil paintings.

The researchers analyzed seven paintings that span 40 years of the painter's career and include masterpieces such as The Virgin of the Rocks and Saint John the Baptist, all on display at the Louvre Museum in Paris. His goal was to gut the keys to fading, the technique with which Leonardo blurred shadows. The results indicate that the master achieved this by adding layers of translucent and lightly colored paint to a mixed white and flesh-colored base. The more darkness he wanted, the more he added. The work has revealed that the almost imperceptible transitions between light and shadow are due to up to 30 layers of paint on which the artist then applied the final varnish.

"The study reflects Leonardo's degree of perfectionism; he had to be a very meticulous artist," explains Armando Solé, a Spanish researcher who works at the ESRF synchrotron in Grenoble (France), the most powerful X-ray source in Europe. Each sheet of paint was one micrometer thick, one thousandth of a millimeter. After each application, the teacher had to wait for it to dry before applying the next one. "He wanted to achieve the greatest possible realism and that took him years of work on each work," explains Laurence de Viguerie, another of the authors of the study. "Many experts point out that he never actually finished any of his paintings," she adds.

Chemical experiments

Solé developed in 2004 the computer program with which it has been possible to analyze the results of the X-rays, count how many layers there are in each area of the face in the paintings and what compounds the master used. "I was doing something like chemical experiments to improve his paintings," De Viguerie explains.

It was also going against the grain. "A painting treatise of the time advised against the use of manganese for shadows, as it dried poorly, but Leonardo used a large quantity in his Saint John the Baptist, instead of the carbon black that was usually used," De Viguerie details.

The researchers always work on a Tuesday, when the museum closes, and can carry out their experiments under the watchful eye of the curators. For a few days they have been analyzing several works by Rafael to try to reveal his secrets now.

Questionnaire

1.- What does translucent mean?

2.- What is the name of the cultural movement of the 16th and 17th centuries in Europe, when this work was painted?

3.- Who was Leonardo da Vinci?

4.- Apparently there are many works by Leonardo in the Louvre Museum in Paris, what country is this city and museum in?

5.- Approximately how many works are exhibited in this museum?

6.-What is the synchrotron?

7.- What is achieved with the sfumato (vanished) technique in painting?

8.- In this investigation on La Gioconda, what has been discovered with the x-rays?