High-resolution X-ray and infrared analyses of a tiny paint fragment from the Mona Lisa's ground layer uncovered Leonardo da Vinci's use of a unique mixture of saponified oil with high lead content, including the presence of the rare compound plumbonacrite, offering new insights into the artistic techniques and materials employed by the master.
In a study published in the Journal of the American Chemical Society, researchers from Université Paris-Saclay, led by corresponding author Victor Gonzalez, unveiled the hidden secrets of Leonardo da Vinci's palette through the examination of a microsample from the ground layer of the world-famous painting, the Mona Lisa. This analysis sheds new light on the techniques and materials used by the Renaissance master.
The research, conducted through high-angular resolution synchrotron X-ray diffraction and micro Fourier transform infrared spectroscopy (FT-IR), offered an unprecedented glimpse into the composition of the painting's ground layer.
The microsample revealed a unique combination of strongly saponified oil with a high lead content, along with a cerussite-depleted lead white pigment. Most notably, the presence of plumbonacrite, a rare compound stable only in an alkaline environment, left a remarkable signature. It suggests that Leonardo da Vinci had embarked on a quest to create a thick paint suitable for covering the wooden panel of the Mona Lisa. He achieved this by treating the oil with a significant load of lead II oxide (PbO).
What makes this discovery all the more intriguing is the ambiguity in Leonardo's manuscripts concerning the use of PbO. The analysis of fragments from another masterpiece, the Last Supper, further substantiates that PbO was indeed a part of Leonardo's palette. The team detected both litharge (α-PbO) and massicot (β-PbO), along with plumbonacrite and shannonite (Pb2OCO3), marking the first-ever detection of the latter in a historical painting.
The researchers sampled a tiny paint fragment from the hidden barb of the ground layer in the upper right zone of the Mona Lisa, concealed by the frame. The sample was embedded in resin for microscopic studies, and a smaller fragment was preserved unembedded in a glass capillary for synchrotron radiation high-angular resolution X-ray powder diffraction (SR-HR-XRPD).
For the analysis of fragments from the Last Supper, the research team employed synchrotron radiation-based attenuated total reflectance micro Fourier transform (ATR-μ-FTIR) and micro X-ray powder diffraction (SR-μ-XRPD) techniques. These revealed a comprehensive view of the materials used in this iconic artwork.
The discovery of plumbonacrite in the Mona Lisa's ground layer represents a significant leap forward in understanding Leonardo's artistic techniques. It not only adds to our knowledge of his palette but also deepens our appreciation of the genius behind the enigmatic smile of the world's most famous painting.
This groundbreaking research reaffirms that, even centuries after their creation, Leonardo's masterpieces continue to reveal new facets of his artistic brilliance.
This article was written with the help of artificial intelligence and has been edited to ensure accuracy and clarity. You can read more about our policy for using AI here.
Reference
Gonzalez, V.; Wallez, G.; Ravaud, E.; Eveno, M.; Fazlic, I.; Fabris, T.; Nevin, A.; Calligaro, T.; Menu, M.; Delieuvin, V.; Cotte, M. X-ray and Infrared Microanalyses of Mona Lisa’s Ground Layer and Significance Regarding Leonardo da Vinci’s Palette. J. Am. Chem. Soc. 2023, April 9, 2023. DOI: 10.1021/jacs.3c07000
AI Shakes Up Spectroscopy as New Tools Reveal the Secret Life of Molecules
April 14th 2025A leading-edge review led by researchers at Oak Ridge National Laboratory and MIT explores how artificial intelligence is revolutionizing the study of molecular vibrations and phonon dynamics. From infrared and Raman spectroscopy to neutron and X-ray scattering, AI is transforming how scientists interpret vibrational spectra and predict material behaviors.
Real-Time Battery Health Tracking Using Fiber-Optic Sensors
April 9th 2025A new study by researchers from Palo Alto Research Center (PARC, a Xerox Company) and LG Chem Power presents a novel method for real-time battery monitoring using embedded fiber-optic sensors. This approach enhances state-of-charge (SOC) and state-of-health (SOH) estimations, potentially improving the efficiency and lifespan of lithium-ion batteries in electric vehicles (xEVs).
New Study Provides Insights into Chiral Smectic Phases
March 31st 2025Researchers from the Institute of Nuclear Physics Polish Academy of Sciences have unveiled new insights into the molecular arrangement of the 7HH6 compound’s smectic phases using X-ray diffraction (XRD) and infrared (IR) spectroscopy.