When researchers set out to study the canvas preparation practices of the Danish masters, they were searching for traces of proteins that indicated the use of animal-based glue—and in eight of the ten paintings they studied, that’s what they found.
“Then, by surprise, we found something completely different,” says study author Cecil Krarup Andersen, a paintings conservator at the Royal Danish Academy, to Maddie Burakoff of the Associated Press (AP).
Seven of the paintings also contained the byproducts of brewing beer, according to a recent study published in the journal Science Advances. Researchers examined works made by Christoffer Wilhelm Eckersberg (sometimes called the “father of Danish painting”) and Christen Schiellerup Kobke during the Danish Golden Age, a time of cultural revitalization in the early 19th century when painters were known for creating realistic scenes with soft light.
With scraps of canvas from the ten artworks as samples, the researchers conducted an analysis to determine which proteins they could detect. They found that seven of the works contained combinations of proteins from yeast, wheat, barley, buckwheat and rye—all telltale signs of a brew.
Rather than actual beer, which was quite valuable at the time, the canvases were likely prepped with leftover mash from local breweries. “Danes made and drank massive quantities of beer during this period, as the water from local rivers and wells was often unsafe,” writes Kate Hull of Science. “That meant lots of leftover beer byproducts.”
These proteins were found only in paintings completed between 1826 and 1833, coinciding with the years Eckersberg and Kobke painted at the Royal Danish Academy of Fine Arts in Copenhagen. “This suggests that this recipe was used in the workshops of the Academy of Fine Arts itself,” says lead author Fabiana Di Gianvincenzo, a heritage scientist at the University of Ljubljana in Slovenia, to Artnet’s Vittoria Benzine.
The mash-based mixture was spread onto the canvases, creating a smooth layer to paint over, says Andersen to the AP. Today, canvases are typically prepared with a mixture called gesso.
At the time, making do with less was common for Danish artists, Andersen tells Popular Science’s Rahul Rao. “Denmark was a very poor country at the time, so everything was reused,” she says. “When you have scraps of something, you could boil it [down] to glue, or you could use it in the grounds, or use it for canvas to paint on.”
Knowing which paintings contain particular proteins is important for conservation work, per the researchers. In the future, experts may be able to use this information for authentication purposes, too.
For Andersen, the new discovery forges a connection between two parts of Danish culture. “What represents Denmark? Well, beer is one of the first things that some people think about,” she tells the AP. “But then also, this particular time and these particular paintings are deeply rooted in our story as a nation.”