Lead was found in the Night Watch

Research reveals how Rembrandt primed his masterpiece to protect it

Dutch experts have published the results of a long-term study of Rembrandt’s masterpiece “The Night Watch”. The painting was subjected to fluorescence and ptychographic nanotomography. We managed to “get” to the lower layers and find out how the master primed the canvas. It turned out that under the paint layer there is quartz, lead and red earth.

A major research project to study the Night Watch, launched in 2019 and called the Night Watch, is needed so that restorers can preserve the famous 17th-century masterpiece for centuries. And for reliable conservation it is necessary to understand the current state of the canvas. The study revealed previously unknown data. It turns out that before taking up the painting, Rembrandt first applied an oil layer with a high lead content to a canvas measuring 379.5 × 453.5 cm, then a mixture of clay, quartz (sand) and red earth (rich in iron oxide – Fe2O3), and then he coated the canvas again with lead oil. The artist also used the technique of priming with a clay-quartz mixture with the addition of earth in some other works. But the discovery of lead oil in the Night Watch was a revelation. Why did the artist need such an experiment?

Obviously, in order for the canvas to be more resistant to moisture, because the customer, Captain Frans Banning Kok, initially placed it in the “Great Hall” (grote zaal in Dutch) of the house of the Dutch Civil Militia Rifle Society – on a long external wall. That is, in a humid environment. Only 55 years later, in 1715, the painting was moved to the Town Hall building: just then it was cut off on the sides so that it fit into the space between two columns.

The artist worked on a large-scale canvas for the newly built building of the “Meeting Hall” of the militia riflemen for three years. It depicts 34 members of society, led by Captain Cock – his figure in a black doublet with a red sash in the center. It was one of seven paintings commissioned from different artists by the militia, but only Rembrandt’s work was distinguished by its amazing play of light and shadow, sense of movement, unusual composition and mystery – and ultimately went down in history. For this work the artist received 1,600 guilders, which was a large sum at that time. The master treated the order with great responsibility already at the preparation stage, although he used available materials.

At first, researchers doubted how many layers of lead oil Rembrandt applied, because ions of this element spread throughout the painting. As a result, we came to the conclusion that there were two: lead oil – clay with soil – lead oil again. The main function of this treatment, according to researchers, is protection from moisture. To “bind” the paint layer to the canvas, Rembrandt could also use an adhesive base, as many of his contemporaries and he himself did. But here the artist departed from the standard method. He probably got the recipe for lead oil from the works of the doctor and writer, Rembrandt’s contemporary, Theodore de Mayerne, who published his notes of conversations with artists, including Rubens and van Dyck. He recommends using lead-rich oil instead of glue if the painting is going to be in a humid environment. If you use glue, the paint may peel off, but lead provides a more reliable bond of materials. And to protect the painting from the reverse side, Rembrandt covered the backdrop with a mixture of beeswax and resin. Moreover, he spent at least 70 hours on this procedure.

Despite the fact that lead oil has indeed proven to be a reliable protection against moisture, it has its drawbacks. Over time, “migrating” heavy metal ions can form so-called “lead soap” – whitish spots – on the canvas. Now a team of researchers, which includes several dozen people from different institutions, has to figure out how to prevent this from happening.