To learn more about how Rembrandt created his famous 17th-century masterpiece “Susanna and the Elders”, art historians and researchers recently compared two imaging techniques that revealed hidden layers in the oil painting which currently hangs in Gemäldegalerie, an art museum in Berlin, Germany.
The painting illustrates the biblical story of Susanna, who is caught bathing by a group of elders and is blackmailed into coming with them. In the tale, Susanna refuses, and the elders are undone by their lies.
Using two imaging techniques, the researchers found that the painting has a “considerable number of overpainted features,” they wrote in the study. For instance, Rembrandt redrew one of the Elder’s arms from his original draft. They also identified a number of chemical elements used in the pigments, such as manganese and iron in the earth-colored pigments, white lead in the distinct whites and mercury in the painting’s vermillion-red pigments.
In the 1930s, researchers took an X-ray of the painting. The results showed that the work of art was replete with pentimenti, or changes the artist made to the painting as he carefully crafted the final scene. Researchers found even more concealed details in 1994, when they used neutron activation autoradiography. This technique involves using a nuclear research reactor to blast the painting with neutrons. By seeing how the neutrons interact with the painting, the researchers can determine what elements are present in the pigments, with the exception of lead-based pigments. Then, they compared their findings with the previous scans of the painting, and tested which method provided the best results.
Interestingly, the elements identified from the X-ray scans were the easiest to interpret, the researchers said. This is likely because many of the individual elements are clearly separated in the results. This technique, known as macro X-ray fluorescence, can also be used to study a broader range of chemical elements compared to autoradiography, they said.
When combined with X-ray scanning, autoradiography can help detect single brush strokes — an important factor in learning about an artist’s technique. “Given the relatively short time and less effort required for investigations using X-ray fluorescence scans, this technique is expected to be applied more frequently in the future than autoradiography,” study lead researcher Matthias Alfeld, a researcher at the University of Antwerp in Belgium, said in a statement.
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