Uncommon compound present in Rembrandt’s The Night time Watch

Rembrandt’s masterpiece The Night time Watch. This discovery, which is a primary within the historical past of the scientific research of work, offers new perception into Seventeenth-century portray approach and the conservation historical past of the portray. The research is revealed in Angewandte Chemie – Worldwide version.

The Night time Watch, painted in 1642 and as we speak displayed within the Rijksmuseum Amsterdam (The Netherlands), is one in every of Rembrandt’s most vital masterpieces and largest murals. Within the framework of the 2019 Operation Night time Watch, the most important analysis and conservation venture ever undertaken for Rembrandt’s masterpiece, a world analysis group joined forces to review how the portray supplies react chemically and with time.

The group of scientists mixed multi-scale imaging strategies in an effort to chemically research the supplies utilized by Rembrandt in The Night time Watch. A X-ray scanning instrument developed on the College of Antwerp (Belgium) was utilized on to the portray, whereas tiny fragments taken from the portray have been studied with synchrotron micro X-ray probes, on the ESRF, the European Synchrotron (France), and PETRA-III facility (Germany). These two varieties of analyses revealed the presence of an sudden organo-metallic compound: lead formates. This compound had by no means been detected earlier than in historic work: “In work, lead formates have solely been reported as soon as in 2020, however in mannequin work (mock-up, contemporary paints). And there, shock: not solely will we uncover lead formates, however we determine them in areas the place there isn’t any lead pigment, white, yellow. We predict that in all probability they disappear quick, because of this they weren’t detected in outdated grasp work till now”, explains Victor Gonzalez, CNRS researcher on the Supramolecular and Macromolecular Photophysics and Photochemistry (PPSM) laboratory (CNRS/ENS Paris-Saclay) and first writer of the paper.

Why did this one not disappear then? For Katrien Keune, head of science at Rijksmuseum and professor on the College of Amsterdam (the Netherlands), this discovering is essential to understanding Rembrandt higher: “In Operation Night time Watch we concentrate on Rembrandt’s portray approach, the situation of the portray and the way we will finest protect it for future generations. The lead formate offers us useful new clues concerning the doable use of lead-based oil paint by Rembrandt and the potential impression of oil-based varnishes from previous conservation remedies, and the advanced chemistry of historic oil work.”

What’s the origin of this compound? Can it present data on Rembrandt’s workshop recipes, or make clear the chemical mechanisms energetic within the layers of outdated paint? To reply these questions, the scientists studied fragments taken from The Night time Watch and mannequin samples ready within the laboratory simulating the painter’s formulations.

They labored with the speculation that Rembrandt used an natural medium (linseed oil) containing dissolved lead oxide (PbO litharge) to reinforce its siccative properties. “Due to the distinctive analytical efficiency of the ESRF, the world’s brightest synchrotron mild supply, we may map the presence of formates at a micrometric scale, and observe their formation over time”, explains Marine Cotte, scientist on the ESRF. The spatial group of the compounds on the micro-scale and the dynamics of their formulation made it doable for the researchers to recommend new hypotheses on the chemical situations of their in situ crystallisation in outdated paint layers.

“Along with offering data on Rembrandt’s pictorial methods, this analysis opens up new avenues on the reactivity of historic pigments, and due to this fact on the preservation of heritage”, explains Koen Janssens, Professor on the College of Antwerp.

The subsequent step for the group is to additional research the origin of those formates and see if they might additionally originate from previous restoration remedies.