Nouchka De Keyser

Nouchka De Keyser is a trained paintings conservator and works as a research scientist at the Rijksmuseum. She is pursuing a joint PhD with the University of Antwerp and the University of Amsterdam, focusing on seventeenth-century Dutch painting technology and the effects of pigment degradation in paintings, using non-invasive imaging techniques. Currently, she is part of Operation Night Watch, a large-scale research and conservation project studying Rembrandt’s The Night Watch (1642).

ABSTRACT

Discovery of Pararealgar and Semi-Amorphous Pararealgar in Rembrandt’s The Night Watch: Analytical Study and Historical Contextualization

N. De Keyser(1,2,3,4,*), F. Broers(1,2,4,5), F. Vanmeert(1,2), A. van Loon(1,6), F. Gabrieli(1), S. De Meyer(2,7), A. Gestels(2,8), V. Gonzalez(9), E. Hermens(10), P. Noble(1), Florian Meirer(5), K. Janssens(1,2,3), K. Keune(1,4)
(1) Rijksmuseum, Conservation & Science, Museumstraat 1, 1070 DN Amsterdam, The Netherlands
(2) University of Antwerp, Department of Physics, AXIS, Groenenborgerlaan 171, 2020 Antwerp, Belgium
(3) University of Antwerp, Faculty of Design Sciences, ARCHES, Mutsaardstraat 31, 2000 Antwerp, Belgium
(4) University of Amsterdam, Van ‘t Hoff Institute for Molecular Sciences,1090GD Amsterdam, The Netherlands
(5) Utrecht University, Inorganic Chemistry and Catalysis, Universiteitsweg 99,3584CG Utrecht, The Netherlands
(6) Mauritshuis, Collection and Science, Plein 29, 2511 CS Den Haag
(7) Royal Institute for Cultural Heritage (KIK-IRPA), Paintings Laboratory, Jubelpark 1, 1000 Brussels, Belgium
(8) University of Antwerp, Department Electromechanics, Research Group InViLab, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerp, Belgium
(9) Université Paris-Saclay, ENS Paris-Saclay, CNRS, PPSM, 91190, Gif-sur-Yvette, France.
(10) Hamilton-Kerr Institute and Conservation and Science Division, Fitzwilliam Museum, University of Cambridge, Trumpington Street, Cambridge, CB2 1RB, United Kingdom

In July 2019, the Rijksmuseum embarked on a large-scale research and conservation project called Operation Night Watch to meticulously study Rembrandt’s The Night Watch (1642). During the research phase, which included multimodal non-invasive chemical imaging and micro-sample analysis, arsenic sulfide compounds were identified. Arsenic sulfide pigments are not commonly associated with Rembrandt’s pigment palette and until now were found only in two paintings from his late period: The Jewish Bride (ca. 1665, Rijksmuseum, Amsterdam), and The Man in a Red Cap (ca. 1660, Museum Boijmans van Beuningen, Rotterdam). In both cases, van Loon et al. discovered the presence of small yellow spherical particles, a purified form of artificial orpiment glass obtained from the dry process method [1].
For The Night Watch, macroscopic X-ray fluorescence (MA-XRF) and macroscopic X-ray powder diffraction (MA-XRPD) mapping, allowed us to discriminate arsenic sulfide pigments

and its associated degradation products in the embroidered buff coat and doublet sleeves worn by Willem van Ruytenburch, one of the central figures, to imitate the golden details. Two paint cross-sections were taken from this area and were analysed with light microscopy, scanning electron microscopy, micro-Raman spectroscopy, and synchrotron radiation-based X-ray powder diffraction imaging. Compared to the small spherical particles in the two other Rembrandt paintings, large angular yellow, and orange-red tabular particles were found in the paint cross-sections from The Night Watch, which were identified by micro-Raman spectroscopy as pararealgar (As4S4), and a semi-amorphous pararealgar. This discovery is new and an addition to Rembrandt’s pigment palette. In this presentation, the identification of the arsenic sulfide pigments will be discussed and contextualized with historical source research on their manufacturing, trade, price, and availability in seventeenth-century Amsterdam.
[1] A. van Loon, P. Noble, A. Krekeler, G. Van der Snickt, K. Janssens, Y. Abe, I. Nakai, J. Dik. Heritage Science. 5, 26, 2017.