Paintings by artists such as Leonardo da Vinci and Sandro Botticelli were protected from yellowing, moisture and cracking by an unexpected ingredient: egg yolk, according to a new study. According to scientists, it is thanks to the proteins in the yolks that their creations have survived for hundreds of years.
A team of scientists from the University of Pisa, the Institute of Chemistry at Italy’s Research Council and the Florence-based inter-university material science and technology consortium have discovered one of the secrets of the greatest of old masters of painting, media reports say. According to an article published in the journal Nature Communications on March 28, the team has proven that some of the greatest old masters of painting, including Leonardo da Vinci and Sadro Botticelli deliberately added an additional ingredient to their oil paints – the yolk of a hen’s egg.
The secret ingredient of the masters of painting
This secret ingredient, due to the proteins contained in it, created a thin layer on the image, which coated the pigment particles and prevented the absorption of moisture from the environment. In addition, the yolk thickened the paint itself. Thus, the addition of egg yolk protected the paintings from yellowing, moisture, and the formation of small cracks as they dried.
According to scientists who have studied such paintings as “Madonna with a carnation” by Leonardo da Vinci or “Lamentation of Christ” by Botticelli, it is thanks to this ingredient that their paintings have survived in good condition for hundreds of years, the scientists point out. The yolk was detected not only in the works of the masters of the Italian Renaissance, but also in the paintings and frescoes of other artists from the 16th, 17th and 18th centuries, such as Albrecht Dürer, Johannes Vermeer and Rembrandt.
The Mystery of Leonardo da Vinci
Egg yolk as a pigment binder has a long history, the British “Guardian” noted on Tuesday, noting that this ingredient was discovered, among others, in on the wall paintings of Nestor’s Palace in Pylos, Greece, dating back to the 13th century BC. In the fifteenth century AD, the yolk as a binder began to be replaced by oil, used, for example, by the Dutch painter Jan van Eyck.
Trace amounts of protein have also long been detected in classic oil paintings, but until now their presence has been considered contamination, notes CNN. ‘Until now, the scientific study of paintings has mainly been aimed at identifying the materials used by painters, but this is not enough to understand the motivations behind the artistic practice,’ said co-author of the new study Ansie Ilaria Bonaduce of the University of Pisa, where for 20 years a research group dealing with cultural goods has been working for years.
Therefore, the scientists decided to “try to discover the secrets of ancient recipes, about which little or nothing has been written”. As part of the study, Bonaduce explained, her team prepared paints with the addition of egg yolk, and then spread them on the surface to analyze their chemical and physical behavior.
The scientists then conducted analyzes in the fields of rheology, which deals with plastic deformations, among others, and calorimetry, i.e. the measurement of heat generated as a result of chemical reactions and physical processes. They also carried out thermogravimetric analysis, which measures the change in mass of a substance depending on changes in temperature or the passage of time.
PAP, CNN, Guardian, Nature Communications
Main photo source: Santa Maria Delle Grazie Basilica