It is very likely that egg yolk was a key ingredient in the oil paints used by the old masters of painting, as it helped prevent yellowing and wrinkling of paintings. A new study found that egg yolks contain proteins that help control the drying process of paint and make it softer, easier to spread. This technique is said to have been used by famous old masters, including Sandro Botticelli and Leonardo da Vinci.
Chemical engineer Ophelia Ranket from the Karlsruhe Institute of Technology in Germany and her colleagues discovered that proteins form a thin layer around the pigment particles and give the paint its ability to repel water. They also soften the paint, so it can be applied in a thicker layer and avoid creasing of the paint.
“Egg yolk proteins can reduce color fastness caused by unwanted moisture uptake from the environment,” the scientists add in a report published in the journal Nature Communications. They emphasize that the eggs act as an antioxidant that slows down the hardening process, and also that the color degrades more slowly.
