A reformulation of nature's recipes in the 15th century tells us about its molecular chemistry
A network forms between egg yolk proteins, water molecules, and pigment clay molecules.
Tempera is a panel used to decorate everything from ancient Egyptian sarcophagi to Indian stone temples. Medium was especially popular with medieval and early Renaissance artists until it was eventually replaced by oil paint. But according to researchers at the Sorbonne in France, while much research has been done on the chemistry of oil paints, temperaments have been largely ignored in the scientific literature.
To solve this problem, according to a recent article in Angewandte Chemie, Sorbonne scientists reconstructed temperamental recipes written by a medieval Tuscan painter. The goal is to gain a more accurate understanding of basic chemistry in order to contribute to ongoing conservation efforts on mood-based artworks from the Middle Ages in particular.

. A dye in which color pigments are mixed with a water-soluble adhesive—usually egg yolk, which is often added with ingredients like a few drops of vinegar to prevent cracking after the mood has dried. The pigment and distilled water are ground with glue directly on the platform or in a bowl. The liquid was sometimes added to compensate for the relatively pungent odor. The artists had to keep adding water as they worked, as the material dries quickly and in those days, the temperature could not be stored, as the yolk began to dry out and the color thickened. While the mood disappeared after 1500, it was periodically rediscovered. Twentieth century artists such as Jacob Lawrence and Andrew White, for example, used mood in their work. The latter has extraordinary durability, and while it contains fewer pigments than oil paints, the paints can provide a jewel-like quality to the final coating. Do not mix well. The coating, even today, is usually mixed through cross hatching or plating techniques. This is why it is often compared to pastel colors or crayons. Reconstruction of a fifteenth <b>century</b> recipe for temperament in the laboratory. Steps to enlarge/reconstruct a 15th century recipe in the lab. Agathe Fanost

According to the authors of the Angewandte Chemie article, most research on temperate paints to date has focused on identifying the adhesives used or examining how temperament paints destroy over time. The researchers were surprised by the key role of this technique in European painting, and no more attention was paid to the molecular interactions between the binder (egg yolk) and various pigments. "The structure and composition of the yolk has been studied in the agricultural and food industries, but despite its use in the dye for centuries, its structure, organization and properties have not been studied in depth in the dye," they wrote. Medieval painters used various pigments, some of which were very toxic. The researchers wisely avoided this and focused their experiments on green earth. Green earth was ubiquitous in medieval Italian woodcuts as a base layer for gilding and an underlayment for flesh-colors. This can be clearly seen in the unfinished book by Michelangelo the Virgin and Child with St. In particular, the outlines of the two angels figures on the left are shown entirely in the base color of green soil. Advertisements

It was recorded in the 14th century. Italian painter named Cennino Cennini. (This is basically a book with different pigments, brushes, techniques, and tricks, as well as lifestyle tips for young aspiring painters.) The soil was green. suspended in water for comparison purposes. The researchers then applied each color to the canvas.

For their analysis, the authors combined two complementary methods: rheology (measurement of how a material deforms) to measure flow characteristics, and titration. NMR to describe the properties and structure of any mixture (Nuclear magnetic resonance imaging uses the magnetic moments of atoms to measure the physical and chemical properties of materials, and the rate at which nuclear spin dissociation provides a kind of fingerprint of molecular dynamics.) Alt = p> A visual comparison of two different mixtures of colors. (Top left) Green soil dye suspended in water. (Top right) Green egg yolk. (bottom left) a water mixture applied to a canvas. /2112/12317-2.jpg "alt =" nature's Fifteenth century Formula tells about molecular chemistry "srcset =" /12 / Tempera3.jpg 2x "> Zoom in / Visually compare two different color mixtures (top left) Green soil pigment suspended in water (top right)) Mood green egg yolk. (bottom left) The water mixture is applied to the fabric. ( Bottom right) Egg yolk temperature applied to fabric, Agate Fanoust et al, 2021

While both groups showed expected shear thinning—the viscosity of a liquid decreasing with increasing pressure, such as hitting a bottle of ketchup to get freer seasoning—was Tempera has a higher viscosity.The authors wrote: “This shows an important synergistic effect between green soil and egg yolk at temperatures.” Its strength is much higher than that of green soil water dispersion.

This is due to the network formed between egg yolk proteins and molecules Water and clay particles in the pigment..Synergy is the result of something that increases the yolk's ability to spread and coat.. Increases the use of yolk as an adhesive a Mood flexibility.

"This study does not claim to solve or answer all questions regarding the importance of adhesive type to dye ability." Instead, it shows the great interest in integrating the two techniques applied to artistic paint materials to create new insights into network link pigment and paint replacement. ">

DOI: Angewandte Chemie, 2021. 10.1002 / anie.202112108 (about the DOI). Why doesn't Apple Touch return an ID to iPhone?

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