Tthe secrets of Rembrandt’s painting technique on Die Nagwag remain lost for now. But researchers tasked with solving the mystery believe they may have found at least a few clues about the perfect recipe for wall filler.
Scientists at AkzoNobel, the Dutch owners of Dulux paint, have been working with conservators at Amsterdam’s Rijksmuseum since 2019 to restore Rembrandt’s masterpiece and build a better picture of how the 17th-century painter worked.
A key objective for Gerard van Ewijk, AkzoNobel’s research and design manager, was to replicate the recipe used by Rembrandt in his impasto technique, where paint is layered thick enough to stand out from the canvas.
The well-defined clothing of Lieutenant Willem Van Ruytenburch in the painting – its full title is The Night Watch Militia under the Command of Capt. Frans Banninck Cocq – is one example of where Rembrandt achieved such an innovative 3D effect.
However, the conclusions of Van Ewijk’s investigations into the paint may raise more questions than answers.
Previous studies of a “small square of paint, smaller than a crumb of paint” discovered egg yoke in the impasto, said Katrien Keune, head of science at the Rijksmuseum. Egg yolk is believed to have been mixed with boiled linseed oil and lead oxide to create what Van Ewijk described as a “kind of mayonnaise”.
After intensive work in the laboratories at the Rijksmuseum and AkzoNobel’s facility on the outskirts of the Dutch capital, Van Ewijk discovered that there was no need for the egg yolk to create the same effect.
A 30:70 ratio of raw linseed oil and white lead creates the perfect impasto paint, raising a perfectly plausible alternative recipe to what was previously assumed to have been used.
“We even questioned whether the previous analysis was correct, but we think the egg was definitely there,” he said. “There are several recipes he could have used… I think one of the outcomes is that you don’t really need to [the egg] so it’s still a bit of a mystery why it’s there”.
But all is not lost. The strenuous efforts of Van Ewijk and his team not only provided insight into the possible range of approaches open to the artist, but also progressed the creation of Polycell, Dulux’s brand of wall filler sold in the UK.
“Seeing how he got such structured paint helps us understand wall filler in a slightly different way,” said Van Ewijk, referring to the new techniques used by his laboratory to improve their efforts to impasto to replicate, to investigate.
The main aim of the extensive research on The Night Watch was to prepare for its first restoration in more than 40 years after a tumultuous four centuries during which it was hidden in a bunker in coastal dunes even at the start of the Second World War.
The first step – ahead of a decision later this year on the removal of multiple layers of varnish applied to the paint over the centuries – was to correct distortion of the canvas seen in the upper left corner.
The damage was apparently incurred during the painting’s stay in the Philips wing of the Rijksmuseum during the main building’s renovation between 2003 and 2013.
The 3.63 meter by 4.37 meter painting has now been removed from a wooden stretcher to which it had been attached with metal hooks since 1975 and mounted on a new one made of a non-reactive material. A decision on next steps is expected in December.
AkzoNobel also advised the Rijksmuseum on the future lighting of the painting and the way to best photograph its many shades of black.
Petria Noble, head of painting conservation at the Rijksmuseum, said AkzoNobel’s experiments “ruled out as nonsense” some previous theories that wax or paint scraps were used by Rembrandt to create the thick impasto paint.
“It’s kind of a missing piece of information that has baffled historians and researchers for a long, long time, so you have to take [step by step]going in the right direction to find out what’s going on,” she said.