The Mona Lisa is the famous Leonardo da Vinci painting of a woman with a mysterious smile. This week, the woman parted her lips to whisper an ancient secret.
Scientists using X-rays to examine the chemical structure of a small part of the painting discovered a technique Leonardo used in the work. An oil paint used for it was a special, new chemical mixture, which suggests that the Italian artist was in an experimental mood when he worked on the painting in the 16th century.
"He loved to experiment, and each of his paintings is completely different technically, "said Victor Gonzalez, a chemist who has studied the chemical element of several works by Leonardo and other artists. The researchers found a rare lead compound (铅化合物) — plumbonacrite, in Leonardo's first layer of paint. The discovery proved that da Vinci most likely used lead oxide to thicken and help dry his paint. The paint in the study is about the thickness of a human hair, lying in the top right area of the painting.
The scientists looked into its atomic(原子的) structure using X-rays, moving particles at the speed of light, permitting researchers to look deeper into the paint structure. " Plumbonacrite is really a fingerprint of his recipe, as it's the first time we can chemically confirm it, " Gonzalez said.
Rembrandt, the Dutch master, may have employed a similar blend in his 17th-century paintings. Gonzalez and fellow researchers have also detected plumbonacrite in his art. It's believed that Leonardo used lead oxide powder, which has an orange color, to thicken his oil paint and speed up drying. "What you will get is an oil that has a very nice golden color, " Gonzalez said. "It flows more like honey. "
But the Mona Lisa — said by the Louvre to be a portrait (肖像) of Lisa Gherardini, the wife of a Florentine silk businessman — There's more to her gaze than meets the eye. "What we are saying is just a little brick in the knowledge, " Gonzalez said.