What physicists know about Rembrandt
Valuable paintings can be examined using modern measuring methods with almost no damage. In Grenoble, Rembrandt’s “The Night Watch” has now been researched with synchrotron radiation. Even neutrons allow completely new insights into old objects of art.
“The Night Watch” is one of the most famous paintings by Rembrandt. The picture, completed in 1642, can be found in the Amsterdam Rijksmuseum to be admired. In order to gain deeper insights into the painting technique of the 17th century, an international team of researchers was allowed to take tiny material samples from the masterpiece and analyze them using X-rays.
The measurements were made with so-called synchrotron radiation at the European Research Center ESRF in Grenoble, France, and at the German Electron Synchrotron (design) of the Helmholtz Association in Hamburg. In addition, the painting was scanned on site with an X-ray scanner developed by Belgian researchers at the University of Antwerp had been developed.
In the journal “Angewandte Chemie” the scientists of the Universities of Amsterdam and Antwerp from a surprising result: they were able to detect a chemical compound that has never been found in an oil painting – lead formatea salt of formic acid.
The researchers suspect that this lead does not come from a color pigment, but from the linseed oil that Rembrandt used to mix the colors. This is supported by the fact that the lead formate was detected precisely in areas of the painting where no lead-containing pigments were used to represent the colors white or yellow. The scientists assume that lead oxide was added to the oil to improve its drying properties. This oxide could then have reacted with other substances, resulting in lead formate.
In any case, the findings allow conclusions to be drawn about Rembrandt’s working methods, emphasizes Professor Katrien Keune, the chief scientist at the Rijksmuseum: “We deal with Rembrandt’s painting technique and the conditions of painting, also to learn how we can best use such paintings for can be preserved for future generations.” For this it is necessary to understand the complex chemistry of historical oil paintings.
With modern scientific methods of analysis, secrets can not only be elicited from paintings. researcher of Leibniz Center for Archeology (Leiza) report that they have gained interesting insights into an 800-year-old piece of jewelry with the help of neutron radiation. The gold-plated pendant was found in a medieval rubbish pit in Mainz’s old town.
With the neutron source of the research reactor FRM II the Technical University of Munich the researchers were able to look inside the object without opening and destroying it. “Due to the centuries of corrosion, the object and especially the locking mechanism were badly damaged,” explains Leiza restorer Matthias Heinzel. “Opening it would have meant destroying it irrevocably.”
The data from the neutron tomography and the Gamma Activation Analysis revealed that inside the jewel are five small packets made of silk and linen. Bone fragments are packed in them. The researchers suspect that they are relics.
Only three other reliquaries of this type, called phylactery, are known so far. “Phylactery” is derived from Greek and means means of preservation or protection.
During the restoration, Heinzel discovered a fragment of a cord in the suspension eyelet. The researchers were able to identify the material of the cord as silk. “This is the first evidence that such pendants were possibly worn around the neck on a silk cord,” says Heinzel. “Using neutron tomography, we were also able to measure the thread thickness and thread spacing of the textiles inside.”
The gold-plated pendant is enamelled on the copper outsides with images of Jesus, the four evangelists, Mary and four female saints. The researchers date it to the late 12th century and assign it to a workshop in Hildesheim, Lower Saxony.