Scientists from the National Museum, the CNRS, the European Synchrotron Radiation Center, the University of Amsterdam and the University of Antwerp have made the discovery of a rare lead formate. “Night value” by Rembrandt. This first discovery in painting research offers new insights into 17th century painting techniques and the history of preservation of artworks. The findings are published in a journal Angewandte Chemie – International Edition.

“The Night’s Watch”, Rembrandt’s iconic masterpiece is now in the State Museum Amsterdam in the Netherlands. Completed in 1642, the painting went through a major research and conservation project known as Operation in 2019.Night’s Watch“. During this project, an international group of researchers studied the chemical reactions and aging of paint materials.

A team of scientists combined multi-scale imaging techniques to chemically study the materials used by Rembrandt. “The Night’s Watch“. An X-ray scan tool developed at the University of Antwerp (Belgium) was applied directly to the table, while small pieces from the table were examined by synchrotron micro-X-ray probes at the ESRF, European Synchrotron (France) and PETRA-III facility (Germany). These two types of analysis revealed the presence of an unexpected organometallic compound: lead formates.

This compound has never been detected in historical charts before: “In charts, lead formats were registered only once in 2020, but in chart models (moquettes, fresh paints). And here’s a surprise: we not only detect lead formats, but also detect lead pigment, white, non-yellow places. We believe they’re probably disappearing quickly, which is why they haven’t been detected in Old Master paintings until now,” explains Victor González, CNRS researcher at the Supramolecular and Macromolecular Photophysics and Photochemistry Laboratory (PPSM) (CNRS/ENS Paris-Saclay) and first author of the paper. .

So why didn’t it disappear? For Katrien Keune, head of research at the Rijksmuseum and professor at the University of Amsterdam (Netherlands), this discovery is key to a better understanding of Rembrandt: “In ‘Operation’.Night’s Watch»» We focus on Rembrandt’s painting technique, the condition of the painting and how we can best preserve it for future generations. The lead format gives us valuable new clues about the possibility of Rembrandt using lead-based oil paints and the potential impact of oil-based varnishes from past conservation operations, as well as the complex chemistry of historical oil paintings.”

What is the source of this compound? Can anyone provide insight into Rembrandt’s workshop recipes or shed light on the chemical mechanisms at work in old paint layers? To answer these questions, the scientists examined the retrieved fragments. “The Night’s Watch” and sample models prepared in the laboratory by imitating the artist’s formulation.

They worked on the hypothesis that Rembrandt used an organic medium (linseed oil) containing dissolved lead oxide (the letter PbO) to improve its drying properties. “Thanks to the unique analytical capabilities of the ESRF, the world’s brightest synchrotron light source, we were able to image the presence of the formats on a micrometric scale and track their formation over time,” explains ESRF research fellow Marin Cott. The spatial organization and formation dynamics of the compounds at the microscale allowed the researchers to propose new hypotheses about the chemical conditions for their in situ crystallization in old paint layers.

“This research, in addition to providing information about Rembrandt’s painting technique, opens up new avenues for the reactivity of historic pigments and therefore for heritage preservation,” explains professor Cohen Jansens of the University of Antwerp.

The team’s next step is to further investigate the origins of these formats and see if they also come from past restoration procedures.