At 3.63 meters (12 feet) in height and 4.37 meters in diameter, the painting is commonly known as The Night Watch is Rembrandt’s largest painting. Centuries after its creation, thanks to advances in modern technology, we still discover the smallest details in its pigments.
A team of researchers from across Europe have found an unexpected molecule while studying the makeup of the paint that makes up the famous Dutch Golden Age artwork.
Thanks to the layers of pigments and other media such as primers and varnishes, pObjects can vary in three dimensions in their chemical composition. As well as scans of the masterpiece’s surface, experts working on the conservation project Operation Night Watch took tiny samples through the layers of the famous painting.
In 2021, two years after the start of the project, Macro XRF Mapping revealed Rembrandts original sketch under the final version of The Night Watch. By shining X-rays on the painting, the technology forces pigments to absorb and then treacherously emit high-energy light, identifying the distribution of different elements within individual layers.
This assignment resulted in many small details that was changed from the original sketch to what we can see today.
However, it wasn’t just the imagery that caught the researcher’s attention. A technique called X-ray powder diffraction showed the presence of lead formats including the rare lead(II) formate Pb(HCOO)2.
Commonly used in the manufacture of white and yellow pigments at the time, it is not at all surprising to find the element lead in a Rembrandt artwork. However, this particular class of lead compounds has only been detected in studies modeling aging from old colors – not in old paintings themselves.
“Not only do we discover lead formats, we identify them in areas where there is no lead pigment, white, yellow”, explained Victor Gonzalez, photochemist at the French National Center for Scientific Research.
“We think they’re probably going away quickly, so they haven’t been spotted in Old Master paintings until now.”
The distribution of lead formates suggests that it was more concentrated in some layers than others and was associated with bright colors.
Gonzalez and colleagues modeled scenarios using various known paint recipes from the period.
“Thanks to the unique analytical power of the ESRF, the world’s brightest synchrotron light source, we were able to map the presence of formates at the micrometer scale and track their formation over time,” explained Beamline scientist Marine Cotte from the European Synchrotron Radiation Facility (ESRF).
Their results suggest that Rembrandt mixed lead(II) oxide into his linseed oil medium for the lighter colors to help them dry. Interactions with other molecules over time turned this into the lead formates. It seems that even great masters of painting like Rembrandt could get impatient with this slow drying medium.
However, it’s also possible that these formats arose from earlier restoration efforts, the team explains.
Previous attempts at restoration have resulted in major changes in the painting actually no night scene at all. Many layers of lacquer mixed with dirt darkened the scene to give this impression, which eventually led to its common name by the late 18th century.
The painting’s official name is District II Militia Company commanded by Captain Frans Banninck Cocqand Operation Night Watch check now how to remove those layers of varnish without disturbing the original painting underneath.
“In addition to information on Rembrandt’s pictorial techniques, this research opens new avenues for the reactivity of historical pigments and thus for the preservation of heritage.” says Koen Janssens, analytical chemist at the University of Antwerp.
In 2021, a missing strip that had been cut out of the artwork was meticulously reconstructed using AI.
“It really gives the painting a different dynamic,” museum director Taco Dibbits told the Associated Press back then. “And what it taught us is that Rembrandt never does what you expect.”
Rembrandt is famous for his exploration of painting materials, techniques and compositions, and the discoveries of Operation Night Watch researchers have demonstrated this time and time again.
This study is published in International edition of Angewandte Chemie.
