Famous Danish painters may have gotten supplies from an unusual source: breweries. A study published Wednesday finds that paintings from 19th-century Denmark included bits of yeast and wheat proteins. Researchers think artists bought the leftover materials from local beer breweries to spread out on their canvases to prime them. The paste would have helped create a smooth surface for the master painters of the time. The researchers used pieces of canvas that had been trimmed from 10 paintings in an earlier conservation project. They say knowing what's on these canvases will help in conserving the paintings.