(ORDO NEWS) — In the second half of the 15th century, Italian painters gradually changed their working technologies: oil paints came to replace egg tempera. But it turned out that not all artists were ready to give up eggs.
It is believed that the history of European oil painting began in the 15th century.
Prior to this, artists painted in tempera, for the preparation of which dry pigments were mixed with a chicken egg (or only with yolk and a little water).
Egg tempera was characterized by instability: the final color of paints and even the safety of the canvas depended heavily on the conditions in which the painting dried.
According to the Italian artist and writer Giorgio Vasari, the Dutch painter Jan van Eyck in the first half of the 15th century thought of diluting paint powders with vegetable oils – and thereby invented a new painting technique.
It is difficult to verify Vasari’s statement: we have examples of earlier use of similar paints, but they are all single. Van Eyck could be both an inventor and a popularizer – and quite successful.
One way or another, in the second half of the 15th century, Piero della Francesca switched to oil painting, largely shaping the tastes and views of the artists of his time.
If all of his early works are made in egg tempera, then later ones are written mainly in oil. Oil paints were more plastic, more comfortable to work with, and behaved more predictably when dried.
Some time ago, chemists studying the paintings of the old masters (as art historians collectively call the artists of Western Europe from the Renaissance to the middle of the 19th century) discovered traces of egg yolk in oil paints.
This applies to the works of Sandro Botticelli, Leonardo da Vinci, Vermeer, Rembrandt and other artists.
There was an assumption that the masters continued to use egg tempera as an underpainting (the original sketch on the main canvas or panel), which was then covered with oil. So traces of egg yolk fell into the top layer of paints.
The authors of which are sure: there was no accident or underpainting. According to them, the artists added chicken egg yolk to oil paints to solve problems with moisture, surface wrinkling and yellowing.
Researchers believe that when Italian painters adopted the technology of making oil paints and oil painting techniques from their northern colleagues, they encountered some problems.
On the one hand, the drying of the painting was more predictable, but on the other hand, in some cases, the surface of the paint layer seemed to be covered with wrinkles.
So, for example, it was with some of the early works of Leonardo da Vinci.
The authors examined Sandro Botticelli’s Lamentation of Christ using gas chromatography, mass spectrometry and amino acid analysis.
Botticelli wrote it at the end of the 15th century, and for a long time it was believed that he used tempera.
Now it turned out that the Florentine combined two techniques: he wrote both tempera and oil. And oil paints were not quite common.
As a result of studying six samples of paint, scientists found that they were all made from a mixture of pigment with vegetable oil, but they also found traces of proteins from the yolk of chicken eggs in all of them.
The yolk was obviously deliberately mixed into the oil paint. Similar data were obtained from a number of other works by old masters.
This looks rather strange, because we have a good idea of the technology for making various paints according to the treatise “The Book of Art” by the Italian artist Cennino Cennini.
He described several methods, but none of them involves adding eggs to oil paints. The question is whether this addition improved the performance of the paints.
Scientists have found that protein compounds from the composition of the yolk of a chicken egg form a thin layer around the pigment particles, which prevents these particles from absorbing water from a humid environment.
The layer of oil paints with this addition became harder, and the surface looked more matte. As a result, the paint layers did not wrinkle during drying.
In addition, the antioxidants in egg yolk helped prevent yellowing during drying by slowing down the reaction between oxygen and oil components.
Most likely, great artists themselves experimented with paint manufacturing technologies, thus improving performance.
Scientists emphasize that the topic of their work is important not only as obtaining new information on the history of art.
Understanding exactly how certain dyes are made is extremely useful both for restorers and for those involved in the storage of painting treasures.
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