An intruder found in Rembrandt's 'Night Watch'

An unusual lead compound never so far identified in ancient paintings has been discovered in Rembrandt's 'Night Watch'. it is a first in the field of scientific investigations applied to works of art, which provides a new vision of the painting technique of the seventeenth century and the history of the conservation of this famous oil on canvas, made in 1642 and now preserved at the Rijksmuseum in Amsterdam.

The study has been published in the international edition of the journal Angewandte Chemie by researchers from the Dutch museum in collaboration with the French National Research Centre (CNRS), the European synchrotron ESRF and the universities of Amsterdam and Antwerp. Rembrandt's painting is currently going through a major research and conservation project called 'Operation Night Watch', which involves an international and multidisciplinary team of experts to analyze how the painting materials used by the artist evolve chemically over time.

Thanks to a first scan of the canvas with a special X-ray scanner developed by the University of Antwerp the researchers identified traces of an unexpected organo-metallic compound, lead formats, in areas of the painting where there are no lead-based pigments. The discovery was confirmed by analyzing some micro samples of the paint with the powerful X-rays of the European synchrotron ESRF in Grenoble and thanks to the Petra-III accelerator, in Germany.

The study speculates that this compound fades rapidly, so it would never have been detected before in ancient paintings. The fact that it is still present on Rembrandt's work may provide valuable clues about the possibility that the Dutch painter used flaxseed oil with dissolved lead oxide to improve its siccative properties, as well as the possible impact of previous restoration treatments.