Experts working on Rembrandt’s painting The Night Watch have found that the artist impregnated the canvas for his famous 1642 militia painting with a lead-containing substance before applying the first ground layer of paint.

Rembrandt knew that his painting would hang on the inner side of the (damp) outer wall of a large hall in Amsterdam and the lead-rich oil impregnation provided better protection against moisture and mold than the glue typically applied on canvasses in the 17th century. 

Such lead-based impregnation has never been observed with Rembrandt or his contemporaries’ work before, Rijksmuseum experts said.

“The discovery underlines Rembrandt’s inventive way of working, in which he did not shy away from using new techniques,” the museum said in a statement.

This research was carried out as part of Operation Night Watch, the biggest and most wide-ranging research project into the history of Rembrandt’s masterpiece.

Work on the project started in summer 2019 and takes place in a specially designed, transparent glass chamber, making it possible for the visiting public to follow the process.