In the process of preserving a 17th-century painting by the Dutch master Rembrandt, scientists have isolated an unexpected chemical within the painting, shedding light on some of the techniques used to create ancient masterpieces.
The Night Watch, possibly Rembrandt’s most famous work of art, was painted in 1642 and is now in the Rijksmuseum Amsterdam in the Netherlands.
As part of a paint conservation and research project called Operation Night Watch, first started in 2019, scientists took a microscopic look at compounds in the paint, leading to an unusual discovery.
In several areas of the painting, they found the presence of lead(II) formate, something that had never before been reported in historic oil paintings.
The discovery was described in a paper published in the peer-reviewed journal Angewandte Chemiethe journal of the German Chemical Society.
Lead-based pigments were commonly used in historical paintings and by Rembrandt, but this specific lead formate was described as “very unusual” in the paper.
Víctor González, researcher at the Laboratory of Supramolecular and Macromolecular Photophysics and Photochemistry and first author of the article, explained in a press release that lead formates have only been reported before in newer model paints. They didn’t expect to find any in The Night Watch.
“And there, surprise: not only did we discover lead formates, but we also identified them in areas where there is no lead, white, yellow pigment,” he said.
“We think they probably disappear fast, that’s why they haven’t been detected in Old Master paintings until now.”
But if this is the case, why didn’t it disappear from Rembrandt’s work?
The answer would not only allow us to learn more about Rembrandt’s techniques, but could provide a pathway to better preservation techniques for modern scientists seeking to extend the life of ancient paintings, the paper’s authors say.
“In Operation Night Watch, we focus on Rembrandt’s painting technique, the condition of the painting and how we can best preserve it for future generations,” Katrien Keune, head of science at the Rijksmuseum and professor at the University of Amsterdam, said in the launch. “Lead formate gives us valuable new clues about the possible use of Rembrandt’s lead-based oil paint and the potential impact of oil-based varnishes from earlier conservation treatments, and the complex chemistry of the paints. historical oil”.
The Night Watch, measuring almost four meters high and 4.5 meters wide, was painted for one of the headquarters of the Amsterdam civic guard, civilian soldiers defending the city.
In the center of the painting, a captain dressed in black gives the order to march to the guards that surround him. Like many of Rembrandt’s works, it is known for its striking use of light and dark, with the glowing figure of a lieutenant at the captain’s side offset by a girl in a yellow dress.
Some of the lead formate was found in the neck of the brightest figure, the lieutenant placed in the center of the canvas.
The researchers compared small fragments of the painting to samples of model paint that they had mixed according to a 1633 recipe, using linseed oil, the most common organic binder used in the 17th century to convert pigments into paint.
They varied their recipe to see which mode of preparation most resembled Rembrandt’s painting, assuming that Rembrandt had used dissolved lead oxide in the paint. Each batch of paint was then spread onto a sheet of glass and allowed to dry for three years.
Using the European Synchrotron Radiation Facility (ESRF), which produces X-rays 100 billion times brighter than those used in hospitals, the researchers were able to trace “the presence of formates down to the micron scale and follow their training over time. ” ESRF scientist Marine Cotte said in the statement.
The researchers say this work has brought them closer to understanding how Rembrandt mixed and sealed his paints, but they hope to do more work in their quest to figure out how to maximize conservation.
“In addition to providing insights into Rembrandt’s painting techniques, this research opens new avenues on the reactivity of historic pigments and thus on heritage preservation,” Koen Janssens, a professor at the University of Antwerp, said in the statement. .
The painting still hangs in the Rijksmuseum in Amsterdam; The exhibit has been set up so that viewers can come and view both the painting and the scientists conducting research in a glass room set up behind it.
Operation Night Watch has made numerous discoveries so far in its deep dive into the painting. According to the website of the Rijksmuseum in Amsterdam, researchers took images of the original sketch below the painting, found the use of a paint that Rembrandt rarely used inside the lieutenant’s yellow coat, and discovered that the degradation of a dog on the right side of the paint it was due to physical abrasion of the paint and not due to fading.