A new study took an intriguing turn when scientists discovered a rare compound called plumbonacrite, which only remains stable in an alkaline environment in the first layer of paint in Leonardo da Vinci's masterpiece, Mona Lisa.
(Photo : AURELIEN MORISSARD/POOL/AFP via Getty Images)
The portrait of Lisa Gherardini, wife of Francesco del Giocondo, known as the Mona Lisa or La Gioconda (La Joconde), painted by Italian artsist Leonardo da Vinci, is displayed at the Louvre museum, in Paris, on June 7, 2023.
Discovering Rare Compound in Leonardo da Vinci's Masterpiece, Mona Lisa
A detailed examination of the paints from the foundational layer of the Mona Lisa painting revealed an extraordinary blend of heavily saponified oil (oil treated with an alkali) with a significant lead content and a lead white pigment devoid of cerussite (PbCO3).
In a remarkable discovery, scientists and art historians in France and the United Kingdom stumbled upon an unusual compound called plumbonacrite. This substance maintained stability solely in an alkaline setting and was detected in the first layer of paint.
Interesting Engineering reported that this finding further supports the notion that Leonardo da Vinci likely incorporated lead oxide powder to enhance his paint's viscosity and drying characteristics.
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Analyzing Leonardo da Vinci's Technique
The study conducted by scientific and artistic experts from France and the United Kingdom reportedly suggests that the Italian artist aimed to prepare a thick paint suited for covering Mona Lisa's wooden panel.
According to the Associated Press, this was achieved by treating the oil with a high load of lead II oxide-PbO. Further investigations led the experts to analyze Da Vinci's techniques in his painting "The Last Supper." In this artwork, the presence of litharge (α-PbO) and massicot (β-PbO) were found.
Beyond the discovery of plumbonacrite, another significant find was the presence of shannonite (Pb2OCO3), marking the first time this substance was identified in a historical painting. These revelations offer a glimpse into Leonardo Da Vinci's painting materials and methods.
The research team reportedly used micro-Fourier transform infrared spectroscopy and high-angular resolution synchrotron X-ray diffraction, which made particles move at almost the speed of light, to accurately determine the chemicals in the sample they were studying.
Victor Gonzalez, the study's lead author and a chemist at the world's top research body, the French National Centre for Scientific Research, told AP that plumbonacrite "is really a fingerprint of his (Da Vinci) recipe."
This is a groundbreaking moment, as it's the first time they "can actually chemically confirm it," according to Gonzalez. After Da Vinci, Dutch artist Rembrandt may have used the same recipe in his painting in the 17th century as Gonzalez and other researchers have also previously found plumbonacrite in his work.
"It tells us also that those recipes were passed on for centuries. It was a very good recipe," Gonzalez noted. The findings were published in the journal ACS Publications on October 11.
The world-famous Mona Lisa painting was painted by Da Vinci between 1503 and 1519 and was hung on French royalty's walls and later in Napolean's bedroom. The portrait, which shows a black-haired woman with enigmatic eyes and a smile, now stares out from behind protective glass in the Louvre Museum in Paris.
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