Chemists from Holland’s University of Amsterdam (UvA) have finally worked out how Rembrandt managed to embellish his Night Watch (1642) painting with striking golden detail.
They used high-tech spectroscopic technology to identify the presence of (yellow) pararealgar and (orange/red) semi-amorphous pararealgar pigments in minute detail in the famous artwork. The research team concluded that the Dutch artist intentionally mixed these particular arsenic sulfide pigments with other pigments to create the golden sheen.
The study was published in Heritage Science, a journal of peer-reviewed research, by Fréderique Broers and Nouchka de Keyser, PhD students at UvA’s Van ’t Hoff Institute for Molecular Sciences, and also researchers at the Rijksmuseum in Amersterdam.
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Rembrandt used the technique to paint the golden threading in the embroidered buff coat and double sleeves worn by one of The Night Watch’s two protagonists, Lieutenant Willem van Ruytenburch.
The discovery of the arsenic sulfide pigments is part of the Operation Night Watch project that began in 2019. The research has unearthed other secrets, including the presence of arsenic and sulfur in Van Ruytenburch’s clothing following an X-ray fluorescence (MA-XRF) scan. As a result, researchers presume Rembrandt used arsenic sulfide pigments realgar [red] and orpiment [yellow].
The research is supported by historical sources detailing the use of arsenic sulfide pigments. It’s now thought that a wider range of such materials was available to artists in 17th-century Amsterdam than previously believed.