Gaby
Leonardo da Vinci famously experimented with the materials he used to prepare grounds and paint layers. A new study has identified a mixture of toxic pigments in the iconic painting the “Mona Lisa” (“La Gioconda”, 1503).
French, British, and Dutch chemists extracted a tiny sample from a hidden corner of the painting. They then analyzed its composition using X-ray diffraction and infrared spectroscopy.
The team discovered not only oil and lead white but also a rare compound called plumbonacrite. This compound forms when oil reacts with lead oxide (PbO).
What Else Did the Scientists Discover?
Researchers say Leonardo likely coated the wooden panel he painted on with a thick layer of lead white. He then added lead oxide to the oil.
This technique doesn’t appear in his writings, but the evidence suggests Leonardo used lead oxide for priming. Hypotheses about this had been proposed before, and now experts have direct evidence of his experiments, according to Science Alert.
He heated lead oxide and dissolved it in linseed or walnut oil, producing a mixture thicker than traditional oil paints that dried faster.
Plumbonacrite had previously been found in micro-samples from the surface of “The Last Supper,” another painting by da Vinci. The compound was also discovered in Rembrandt’s “The Night Watch” (1642).
“The Last Supper” by da Vinci – another famous painting where toxic plumbonacrite was found
This discovery shows how modern analytical methods can uncover secrets in ancient masterpieces and reinforces Leonardo’s technical ingenuity across painting, mathematics, chemistry, engineering, and more.
“He loved to experiment, and each of his paintings is technically completely different,” said researcher Victor Gonzalez of the Paris Institute of Chemistry.
The results of the study were published in the Journal of the American Chemical Society.
