The plumbonacrite, the secret ingredient of Rembrandt's paintings | Culture

Rembrandt was not a chemist, but like all artists, he mixed pigments and oils to achieve the desired effect in his paintings. In your case, the relief achieved by applying thick layers of paint to the canvas - the filling - to accentuate the feeling of chiaroscuro. The "master of light", as the Dutchman was called, was helped in the seventeenth century by an ingredient that had not been seen in his fabrics until today: plumbonacrite, a mineral containing lead. Rembrandt did not buy it. It is the product of the synthesis derived from adding lead oxide to the white pigment of lead, and also to the organic solvent, in this case, linseed oil, which was used regularly. When the 350th anniversary of his death is completed, his secret has been discovered by scientists at the Technical University of Delft and The Rijksmuseum, with the help of the European Synchrotron Radiation Laboratory (ESRF in its acronym in English).

The plumbonacrite has been found in some paintings of the 20th century, as well as in the work of Vincent van Gogh, where it appears in a lead red pigment, very degraded. "It's not an ingredient that Rembrandt I could acquire in the market. He experimented with colors. I did not know about chemistry in the strict sense, but I was looking for the reflection of light in the paint applied with the brush, and the plumbonacrite was formed due to the mixtures I made, "says Annelies van Loon, a researcher at Delft and the Rijksmuseum. "We have taken three oil paintings from different years and museums. Are the Portrait of Marten Soolmans (1634), from the Rijksmuseum, Bathsheba with David's letter (1654), of the Louvre, and Susanna (1636) of the Mauritshuis gallery, in The Hague. Thanks to the synchrotron, the research has been minimally invasive, and my job has been to prepare samples of 0.1 millimeter filling to be able to work, "he says.

With the light of the synchrotron of the European ESRF laboratory, which is based in Grenoble (France), it was possible to unravel the morphology and layers of the filling. Hence, according to the researchers, as "the presence of plumbonacrite is indicative of an alkaline environment, relying on historical texts, we believe that Rembrandt added lead oxide (litharge) to the oil for this purpose, converting the mixture into a paint similar to a paste ", says the study, published by the Technical University of Delft. "We do not know if Rembrandt always used the same recipe for the filling, and that is why we will analyze other of his paintings, along with those of his circle. We will also see those of Vermeer and Frans Hals, both masters of the Golden Age ", adds Van Loon.

The discovery explains the consistency of Rembrandt's filling, and can contribute to improving the conservation of his works and solving the attribution problems. He was also a good teacher for the students of the painting workshop he owned in Amsterdam, and its official catalog includes 340 authentic titles. They were certified in 2014 by the Rembrandt Project, a monumental study funded by the Dutch Government, which invested 46 years in reviewing all the pictures considered yours. Several of them are already awarded To the workshop, even in large collections. In the Mauritshuis gallery, for example, only 11 of its 18 rembrandts They have turned out to be authentic.

The study coincides with the start of Rembrandt Year, dedicated to remember him in his country three and a half centuries after his death, with exhibitions in the Rijksmuseum and the House-Museum of the painter (Amsterdam), Mauritshuis, Museum of Friesland (Leeuwarden) and De Lakenhal (Leiden)