John Taylor of Canada's National Research Council said there were no signs of any brush stroke. "That includes the very fine details of the embroidery on the dress, the hair," he said. "This is the 'je ne sais quoi' of Leonardo. The genius. We don't know how he applied it."
The scan even revealed Leonardo's first conception of Mona Lisa.
"The 3-D imaging was able to detect the incised drawing to provide us with da Vinci's general conception for the composition," said Christian Lahanier, head of the documentation department of the French research center.
The artist brought the painting to France in 1517. It has been in the Louvre Museum since 1804.
The data collected in 16 hours of scanning, starting in 2004, took a year to analyze. It shows warping in the poplar panel Leonardo used as his canvas, but the Mona Lisa smile is not threatened.
"We didn't see any sign of paint lifting," Taylor said. "So for a 500-year-old painting, it's very good news. And if they continue to keep it the way they have in an environment-controlled chamber, it could remain like that for a very long time."
Menu said all the secrets behind the enigmatic painting have yet to be revealed, including Leonardo's techniques.
"We particularly want to understand how he painted his shadows, the famous 'fumato' effect," Menu said.
