19th century painters may have primed their canvases with beer-brewing leftovers

Beer breweries’ trash may have been Danish painters’ treasure.

The base layer of several paintings created in Denmark in the mid-1800s contains remnants of cereal grains and brewer’s yeast, the latter being a common by-product of the beer brewing process, researchers report May 24 in Science Advances. The finding hints that artists may have used the leftovers to prime their canvases.  

Records suggest that Danish house painters sometimes created glossy, decorative paint by adding beer, says Cecil Krarup Andersen, a conservator at the Royal Danish Academy in Copenhagen. But yeast and cereal grains have never been found in primer.

Andersen had been studying paintings from the Danish Golden Age, an explosion of artistic creativity in the first half of the 19th century, at the National Gallery of Denmark. Understanding these paintings’ chemical compositions is key to preserving them, she says. As part of this work, she and colleagues looked at 10 pieces by Christoffer Wilhelm Eckersberg, considered the father of Danish painting, and his protégé Christen Schiellerup Købke.

Canvas trimmings from an earlier conservation effort allowed for an in-depth analysis that wouldn’t have otherwise been possible, since the process destroys samples. In seven paintings, Saccharomyces cerevisiae proteins turned up, as well as various combinations of wheat, barley, buckwheat and rye proteins. All these proteins are involved in beer fermentation (SN: 9/19/17).

Tests of an experimental primer that the researchers whipped up using residual yeast from modern beer brewing showed that the mixture held together and provided a stable painting surface — a primary purpose of a primer. And this concoction worked much better than one made with beer.

Beer was the most common drink in 1800s Denmark, and it was akin to liquid gold. Water needed to be treated prior to consuming and the brewing process took care of that. As a result, plenty of residual yeast would have been available for artists to purchase, the researchers say.

If the beer by-product is found in paintings by other artists, Andersen says, that information can help conservators better preserve the works and better understand the artists’ lives and craftsmanship. “It’s another piece of the puzzle.”