The great Renaissance masters added
egg yolk to their oil paints in order to protect their
masterpieces against yellowing and humidity and to prevent the
formation of cracks during drying, according to research
published in Nature Communications and led by Italian
"So far, scientific investigations of paintings have mostly been aimed at identifying the materials used by painters, but this is not enough to understand the reasons behind the artistic practice," Ilaria Bonaduce, an associate professor at the Department of Chemistry and Industrial Chemistry at the University of Pisa, told ANSA.
In their study, the researchers from the University of Pisa, the National Research Council's Institute of Chemistry of Organometallic Compounds and the National Interuniversity Consortium for Materials Science and Technology (Instm) in Florence focused on the practice of adding egg yolk to oil paint, which was used by many famous painters, from Leonardo and Botticelli to Durer, Vermeer and Rembrandt, among others.
"In the lab, we prepared paints with the addition of the yolk and laid them out to study their chemical and physical behavior," said Bonaduce.
The scientists found that the egg proteins coat the pigment particles and prevent the absorption of ambient moisture.
In addition, the yolk makes the colour mixture more consistent, prevents small cracks from forming during drying, and prevents the pigments from yellowing.
"Now we are continuing to work using other analytical techniques to investigate the microstructure, so we can then move on to study famous paintings," Bonaduce continued.
"Samples of Sandro Botticelli's 'Lamentation over the Dead Christ,' preserved in Munich, are already available, but we will also work on other works by Titian and Ghirlandaio," she said.
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