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“Old Masters” such as Leonardo da Vinci, Sandro Botticelli, and Rembrandt may have used proteins, specifically egg yolk, in their oil paintings, according to a recent study.
Trace amounts of protein residue have been found in classic oil paintings for years, but it was often considered contamination. However, a new study published in the journal Nature Communications suggests that the inclusion of protein was intentional, shedding light on the technical knowledge of the Old Masters and their paint preparation techniques.
The study’s author, Ophélie Ranquet, explained that there is limited information available on this topic, and no in-depth scientific research has been conducted before. However, the results of this study demonstrate how even a small amount of egg yolk can significantly change the properties of oil paint, showing the potential benefits for artists.
Adding egg yolk to oil paint can have long-lasting effects that go beyond aesthetics, according to the researchers. Compared to the medium called tempera, which combines eggs with other ingredients, oil paint offers more intense colors, smoother transitions, and a longer drying time. However, oil paint is also more susceptible to color darkening and damage from light exposure.
During the study, the researchers recreated the process of paint-making using four ingredients: egg yolk, distilled water, linseed oil, and pigment. By mixing these ingredients, they were able to replicate two historically significant colors, lead white and ultramarine blue.
The addition of egg yolk to the paint resulted in significant changes in its behavior and viscosity. For example, the presence of egg yolk made the paint more resistant to humidity, easier to apply, and allowed for the creation of high impasto paintings. The study suggests that the Old Masters may have deliberately added egg yolk to their oil paint to achieve these desired effects.
One of the paintings observed during the study, Leonardo da Vinci’s “Madonna of the Carnation,” shows evident wrinkling on the faces of Mary and the child. This wrinkling occurs when the oil paint starts to dry from the surface down.
According to the study’s findings, the addition of egg yolk to oil paint can prevent wrinkling, even with the same amount of pigment. This suggests that artists like Leonardo da Vinci may have discovered and utilized the beneficial effects of egg yolk in their paintings.
“Adding egg yolk had such desirable effects on oil paint that the presence of proteins in the works of art might indicate intentional use rather than contamination,” the study proposes. These preliminary findings could generate further interest in this understudied topic.
Maria Perla Colombini, a professor of analytical chemistry at the University of Pisa, commended the study’s insights into old painting techniques. She noted that this research contributes not only to the preservation of artworks but also to a better understanding of art history.
Top image: The “Mona Lisa” by Leonardo Da Vinci
