Chemistry tools reveal surprise lead layer under a Rembrandt masterpiece

The Dutch 17th century master Rembrandt first laid down a lead-containing substance on his famous painting The Night Watch before he applied the first layer of paint to the canvas, according to new analysis led by researchers in the Netherlands. The team used x-ray fluorescence and a computational microscopic imaging method called ptychography to uncover this technique, which had never been observed before with Rembrandt or his contemporary artists.

The traditional way of preparing a canvas in the Netherlands in the 17th century involved animal glue, which had been documented to fail under humid conditions. But in The Night Watch there is no indication of a glue-size layer in any of the paint samples. Instead, the canvas appears to have been impregnated with a lead-containing oil.