Operation Night Watch
By: Josh Burleson
Tags: Technology, Innovation, History, Art, Museums

An Unparalleled Restoration

“The Operation Night Watch research team use the very latest technologies and continually push the boundaries of what was thought possible.” — Museum Director Taco Dibbits

The research phase of Operation Night Watch kicked off in 2019 with the construction of an ultra-transparent glass chamber, designed by French architect Jean Michel Wilmotte. Once the painting was secure inside the chamber, its frame was removed, and advanced imaging techniques were administered to learn what secrets were contained within.

Using macro X-ray fluorescence scanning and hyperspectral imaging, The Night Watch was scanned millimeter-by-millimeter to analyze chemical elements in the paint and pigments used. A total of 56 scans were performed — each requiring 24 hours to complete — in order to cover the entire surface of the painting. This type of equipment is crucial to a project like this because in being able to break down the elemental composition within the paint, the museum can determine the best way to preserve the painting.

The macro-XRF scans also yielded important details within the painting. It was determined that the chemical elements present are lead, iron, and calcium. The iron scan also uncovered feathers on a helmet of one of the background characters that Rembrandt painted out that cannot be seen by the naked eye, nor were they visible in the X-radiographs that were taken in the 1970’s. It was also discovered that Rembrandt used an arsenic-based pigment for some areas, such as gold embroidery on the clothing, that at the time was mainly used for paintings of still life, such as fruit and flowers.

Using a macro X-ray Powder Diffraction scanning process, the museum was able to break down pigment composition within the elements to an even further degree than the maco-XRF scans. By deflecting and reflecting radiation as it detects a pigment, the macro-XRPD identifies different crystalline structures of pigments at an atomic level, and makes it possible for Operation Night Watch to map the degradation conditions within the layers of paint.

In order to see the buildup of paint layers and to determine how the paint has changed over time, the researchers chose very specific areas to extract samples measuring around 200-micrometers, (1 micrometer is 0.000001 meters) too small to be seen by the naked eye. Once extracted, the sample is embedded in a small block of resin, then polished and photographed to be examined using microscopic techniques.

Probably the most incredible part for the followers of Operation Night Watch (so far) occurred in May, when the Rijksmuseum published a massive, 44.8 gigapixel image of The Night Watch, comprised of 528 different still photos. According to the museum, “The 24 rows of 22 pictures were stitched together digitally with the aid of neural networks.” The photo is so enormous, that zooming in allows the viewer to see individual brushstrokes and flecks of paint.

Currently, researchers are using a robotic camera to take more than 8,400 photos at a resolution of 5-micrometers. To put that in perspective, Rijksmuseum Senior Scientist Robert Erdmann explains, “A human red blood cell is 8-micrometers wide, so it would take a 2.2 array of our pixels to hold one human red blood cell.”

Once all the photos have been taken, they will be digitally assembled to form a single image, allowing researchers to view individual pigment particles and aid in preservation.

While COVID-19 has slowed Operation Night Watch to the point that the restoration phase, which was originally to begin shortly following summer 2020 has been pushed back to early 2021, the study of the painting has continued both virtually as well as in-person, albeit with greater social distance. Aided by advanced technology, as well as a remarkable team of experts, the Rijksmuseum has taken monumental strides that will not only guide them through the process of restoring and preserving The Night Watch for generations, but will also assist them in learning more than ever before about Rembrandt’s magnum opus.