More than light and shadow: the subtle details of Rembrandt's mastery

High-tech analysis reveals sophisticated use of pigments

15 September 2025

In a recently published article in the journal NPJ Heritage Science, researchers from the Rijksmuseum and the University of Amsterdam show how Rembrandt tuned his choice of pigments to arrive at a high-contrast, realistic representation of his subjects. He thus created his “chiaroscuro” effect in a rather remarkable way. They conclude this based on research into striking details in the costume of Lieutenant Willem Van Ruytenburch in The Night Watch.

The study was part of the research of PhD candidate Nouchka De Keyser. She recently obtained her doctorate under the supervision of Prof. Katrien Keune, head of research at the Rijksmuseum and professor at the UvA's Van 't Hoff Institute for Molecular Sciences. The work was also part of the major scientific study of Rembrandt's masterpiece Operation Night Watch and involved cooperation with several other universities and institutions.

Playing with light, shadow and context

Element analysis. An MA-XRF scan reveals the distribution of the chemical elements present in the painting, some of which are shown here. This forms the basis for further analysis of Rembrandt's use of pigments. Image: HIMS / NPJ Heritage Science, courtesy of the Rijksmuseum.

The paper in NPJ Heritage Science describes how high-tech macroscopic imaging techniques helped to gain insight into Rembrandt's painting process in Van Ruytenburch's embroidered costume. Identification of the chemical compounds present and their microscopic structure revealed how Rembrandt applied a refined palette of pigments. These include lead white, lead-tin yellow, yellow and red ochres, vermilion, arsenic sulphide pigments, red lacquers, smalt and azurite.

The research shows that Rembrandt used all these pigments in a consistent, systematic way to achieve pictorial unity. Experts use this term to indicate that the elements in a painting form a natural, harmonious ensemble, where everything feels “right”. Lighting is a crucial aspect in this regard. In order to convincingly render gradations of light and shadow, Rembrandt applied the pigments in groups to achieve tonal contrasts between the illuminated and shaded areas.

In this way, he created an optical phenomenon that is now known as the simultaneous contrast effect. It is a way of achieving colour variations without mixing different types of paint or tonal values. Rembrandt always used the same pigment (such as yellow ochre), but placed it strategically in light and dark areas. This makes the colour appear lighter or darker, depending on the surrounding tones and contrasts.

Historical confirmation

The researchers' observation corresponds with a note about Rembrandt's painting technique by his pupil Samuel Van Hoogstraten. In the fifth chapter of his treatise Inleyding tot de hooge schoole der schilderkonst: anders de zichtbaere werelt (Introduction to the High School of Painting: or the Visible World), Van Hoogstraten writes that Rembrandt was a master at combining complementary colours.

Pigment analysis. At the left is the body of Van Ruytenburch’s costume as it can be seen under daylight illumination at the Rijksmuseum. The image at right depicts a composite overlay of the results of the spectral analysis, where the (false) colors represent different pigments used. It demonstrates Rembrandt’s ability to manipulate colours and shows how he consistently chose specific pigment groups to portray the light and shadow tones, and tonal variations in between. From the most illuminated parts to the deepest shadows, a systematic application of pigments and careful layering can be observed, contributing to the creation of a convincing chiaroscuro, ultimately achieving compositional unity. Image: HIMS / NPJ Heritage Science, courtesy of the Rijksmuseum.

He advises artists to follow Rembrandt's example: do not allow light and dark to blend too much, but group them in a clever way: ‘let your strongest lights be accompanied by lesser lights, I assure you that they will shine all the more beautifully; let your deepest darks be surrounded by clear browns, so that they may contrast all the more powerfully with the strength of the light.’

This interplay of light, shadow and context gave Rembrandt's paintings a natural depth, volume and three-dimensionality. Although the concept was only named later, scientists such as Ibn al-Haytham and Leonardo da Vinci were already familiar with the principle that colours and brightness are perceived differently depending on their surroundings. Rembrandt consciously applied this to create a convincing chiaroscuro (light-dark) effect.

Degradation research

Advanced research techniques also made it possible to identify ageing processes in The Night Watch. The presence and distribution of lead arsenates (mimetite Pb₅(AsO₄)₃Cl and schultenite Pb(HAsO₄)), calcium oxalates (weddelite, CaC₂O₄·2H₂O) and a potassium-containing lead sulphate (palmierite K₂Pb(SO₄)₂) were established. These compounds were formed over time by the degradation of the pigments originally used. This enabled the researchers to map the influence of the degradation products on the representation of Van Ruytenburch's costume and Rembrandt's light-dark contrasts better than ever before.

High-tech methods

The conclusions from the research stem from three applied high-tech analytical methods: MA-XRF, MA-XRPD, and RIS.

MA-XRF (macro X-ray fluorescence scanning) allows scientists to study paintings without touching them. A scanner with an X-ray source and two detectors moves millimetre by millimetre across the painting to map the chemical elements present with great accuracy. From the distribution of the elements in a painted area, researchers can deduce the pigments used – for example, the presence of mercury indicates the use of vermilion red (HgS).

MA-XRPD (Macro X-ray Powder Diffraction scanning) provides additional information that makes it possible to distinguish between pigments with the same elemental composition. The technique can distinguish differences in crystal structure – the regular structure in which the atoms of a pigment are arranged. MA-XRPD also provides insight into the condition of the paint layers by identifying and localising degradation products.

Reflectance Imaging Spectroscopy (RIS), also known as hyperspectral imaging, complements MA-XRF and MA-XRPD. It is a non-invasive and non-destructive technique that uses ordinary daylight instead of X-rays. Special cameras (imaging spectrometers) record how the materials in the paint layers reflect or scatter daylight. This allows pigments and binders to be identified and mapped across the entire surface of the painting.

Paper details

Nouchka De Keyser, Annelies van Loon, Francesca Gabrieli, Frederik Vanmeert, Fréderique T. H. Broers, Petria Noble, Steven De Meyer, Arthur Gestels, Victor Gonzalez, Mitra Almasian, Inez van der Werf, Erma Hermens, Koen Janssens & Katrien Keune: Illuminating Rembrandt’s Chiaroscuro in The Night Watch: the painting process of Van Ruytenburch’s costume. npj Heritage Science volume 13, Article number: 406 (2025). DOI: 10.1038/s40494-025-01874-w

More than light and shadow: the subtle details of Rembrandt's mastery

Playing with light, shadow and context

Historical confirmation

Degradation research

Paper details

See also

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