Scientists have used chemistry and physics to uncover a secret of Renaissance painters. Chemical engineer Ophélie Ranquet and her team at the Karlsruhe Institute of Technology in Germany created two oil-egg recipes to compare with plain oil paint. One mixture contained fresh egg yolk mixed into oil paint, while the other blend involved grinding pigment into the yolk, drying it, and mixing it with oil. The team subjected each medium to a battery of tests that analyzed its mass, moisture, oxidation, heat capacity, drying time, and more. The yolk’s proteins, phospholipids, and antioxidants helped slow paint oxidation, which can cause paint to turn yellow over time, according to the team’s report in Nature Communications on March 28.
