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Rijksmuseum uncovers hidden sketch during examinations of Rembrandt’s The Night Watch

The calcium map, made with the Macro-XRF scanner where you can see Rembrandt’s sketch in the upper part

Operation Night Watch has seen a team of researchers working at the Rijksmuseum for the past two-and-a-half years, meticulously mapping Rembrandt’s The Night Watch using the most advanced imaging techniques and computer technology.

Completed in 1642 it is a giant of a painting measuring 3.63m x 4.37 and is named after the Military Company of District II depicted in the scene, also known as The Night Watch. The museum says The Night Watch is one of the most important painting in the world and hangs in its Gallery of Honour.

During the process the public have been able to watch the conservation in the museum, through a transparent glass chamber, and online. Photograph courtesy of Rijksmuseum

During the research the conservationists used a ‘calcium map’ of the work to see Rembrandt’s preparatory sketch as the artist’s use of chalk-rich paint could be identified by the latest scanning technology. They also used macro-XRF imaging and Fiber Optic Reflectance Spectroscopy (FORS).

Operation Night Watch team using Fiber Optic Reflectance Spectroscopy

Using FORS, the painting was illuminated and the light reflected from the painting is collected with a fibre optic with the pigment and binding media within it each reflecting the light back in a different way.

Their work has produced an unprecedented volume of data that offers a vastly improved understanding of the creation process and the painting’s current condition.

Like looking over Rembrandt’s shoulder

They say the process was like being allowed to look over the artist’s shoulder as he took the first steps in the making of a masterpiece.

The discovery of the sketch represents a breakthrough in this research with conservationists able to look beneath the surface of the paint better than ever before and understand for the first time of how the painting was made.

“It is fascinating to see Rembrandt searching for the right composition. We have discovered the genesis of The Night Watch,” said Taco Dibbits, Director of the Rijksmuseum. 

Uncovering the sketches

The conservationists said the underpainted sketch corresponds with their understanding of Rembrandt’s spontaneous approach to composing directly on the canvas itself.

They found the artist had applied a brown ‘quarts’ ground and used a beige paint with a high chalk content for his rough sketch. To date, no other paintings by Rembrandt have been discovered that were prepared using this type of paint.

Petria Noble, the Rijksmuseum’s Head of Paintings Conservation, said: “Each new detail gives us another insight into Rembrandt’s creative process: his original idea, his thought processes and his material and artistic choices.

Setting a new standard

“An all-encompassing approach such as this would have been impossible even a few years ago, which means Operation Night Watch is setting a new standard for the study of painting. All these discoveries now prompt us to look at Rembrandt’s other paintings with different eyes – we now know what we should be looking for.”

The Operation Night Watch team believe Rembrandt must have spent a considerable time in his search for the ideal composition for this large painting. Previous studies of The Night Watch had already revealed dozens of pentimenti, or modifications made by the artist himself.

Compositional changes

Now, using the latest imaging techniques, Operation Night Watch has discovered even more changes.

“We can see, for example, that Rembrandt originally painted feathers for the helmet of militiaman Claes van Cruijsbergen, but later painted them over. The artist also adjusted the leg position of Rombout Kemp – the many scans revealed that the leg initially was painted in a different position at an earlier stage. There are also indications of the presence of an additional sword between the captain and the lieutenant and it has become clear that Rembrandt originally indicated have a larger number of spears projecting above of company.” 

The condition of The Night Watch

A 44.8 gigapixel image allows scientists to study the painting’s detail remotely (link in photo)

As well as providing an understanding of Rembrandt’s working methods, this detailed examination of The Night Watch has shed a light on the condition of the painting.

“In many areas the paint is still in an excellent state, an example being the richly decorated coat of Willem van Ruytenburch. Other areas, however, are in poor repair, partly as a result of the many treatments The Night Watch has undergone since the 17th century – it is more than likely, for example, that the removal of varnish in the past led to the dissolving of paint at some locations.”


Looking at The Night Watch today viewers will notice several clearly defined ripples in the upper left corner of the canvas. These deformations they say developed at the beginning of this century when the painting was hung in the Phillips Wing during the refurbishment of the main museum building.

“They are probably the result of excessive climatic fluctuations in the gallery during this period. These deformations need to be addressed and can be remedied without any danger to the painting.”

This treatment will begin on 19 January 2022, when The Night Watch will be onto a new strainer.

Once this process is complete the museum will decide whether more conservation treatment on the painting should be carried out.

About the author – Adrian Murphy

Adrian is the Editor of MuseumNext and has 20 years’ experience as a journalist, half of which has been writing for the cultural sector.

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