Sat. Sep 23rd, 2023
An Old Master's secret ingredient? Egg yolk, new study suggests

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“Outdated Masters” akin to Leonardo da Vinci, Sandro Botticelli and Rembrandt could have used proteins, particularly egg yolk, of their oil work, in line with a brand new research.

Hint portions of protein residue have lengthy been detected in basic oil work, although they had been usually ascribed to contamination. A new study published Tuesday within the journal Nature Communications discovered the inclusion was probably intentional — and sheds gentle on the technical information of the Outdated Masters, essentially the most expert European painters of the sixteenth, seventeenth, or early 18th century, and the way in which they ready their paints.

“There are only a few written sources about this and no scientific work has been carried out earlier than to analyze the topic in such depth,” stated research creator Ophélie Ranquet of the Institute of Mechanical Course of Engineering and Mechanics on the Karlsruhe Institute of Know-how in Germany, in a cellphone interview. “Our outcomes present that even with a really small quantity of egg yolk, you may obtain an incredible change of properties within the oil paint, demonstrating the way it might need been helpful for the artists.”

Merely including some egg yolk to their works, it seems, might have long-lasting results that went past simply aesthetics.

In contrast with the medium formulated by historical Egyptians referred to as tempera — which mixes egg yolk with powdered pigments and water — oil paint creates extra intense colours, permits for very easy coloration transitions and dries far much less rapidly, so it may be used for a number of days after its preparation. Nevertheless, oil paint, which makes use of linseed or safflower oil as an alternative of water, additionally has drawbacks, together with being extra vulnerable to paint darkening and harm attributable to publicity to gentle.

As a result of making paint was an artisanal and experimental course of, it’s attainable that the Outdated Masters might need added egg yolk, a well-known ingredient, to the newer sort of paint, which first confirmed up within the seventh century in Central Asia earlier than spreading to Northern Europe within the Center Ages and Italy throughout the Renaissance. Within the research, the researchers recreated the method of paint-making by utilizing 4 elements — egg yolk, distilled water, linseed oil and pigment — to combine two traditionally common and important colours, lead white and ultramarine blue.

“The addition of egg yolk is helpful as a result of it could actually tune the properties of those paints in a drastic means,” Ranquet stated, “For instance by exhibiting growing old in another way: It takes an extended time for the paint to oxidize, due to the antioxidants contained within the yolk.”

The chemical reactions between the oil, the pigment and the proteins within the yolk straight have an effect on the paint’s habits and viscosity. “For instance, the lead white pigment is kind of delicate to humidity, however when you coat it with a protein layer, it makes it much more immune to it, making the paint fairly straightforward to use,” Ranquet stated.

“However, when you needed one thing stiffer with out having so as to add plenty of pigment, with a little bit of egg yolk you may create a excessive impasto paint,” she added, referring to a portray approach the place the paint is specified by a stroke thick sufficient that the brushstrokes are nonetheless seen. Utilizing much less pigment would have been fascinating centuries in the past, when sure pigments — akin to lapis lazuli, which was used to make ultramarine blue — had been dearer than gold, in line with Ranquet.

A direct proof of the impact of egg yolk in oil paint, or lack thereof, may be seen in Leonardo da Vinci’s “Madonna of the Carnation,” one of many work noticed throughout the research. At the moment on show on the Alte Pinakothek in Munich, Germany, the work reveals evident wrinkling on the face of Mary and the kid.

“Oil paint begins to dry from the floor down, which is why it wrinkles,” Ranquet stated.

One motive for wrinkling could also be an inadequate amount of pigments within the paint, and the research has proven that this impact may very well be averted with the addition of egg yolk: “That’s fairly superb as a result of you may have the same amount of pigment in your paint, however the presence of the egg yolk modifications every little thing.”

As a result of wrinkling happens inside days, it’s probably that Leonardo and different Outdated Masters might need caught onto this specific impact, in addition to further helpful properties of egg yolk in oil paint, together with resistance to humidity. The “Madonna of Carnation” is one among Leonardo’s earliest work, created at a time when he might need been nonetheless attempting to grasp the then newly common medium of oil paint.

One other portray noticed throughout the research was “The Lamentation Over the Lifeless Christ,” by Botticelli, additionally on show on the Alte Pinakothek. The work is usually made with tempera, however oil paint has been used for the background and a few secondary components.

“We knew that some elements of the work present brushstrokes which are typical for what we name an oil portray, and but we detected the presence of proteins,” Ranquet stated. “As a result of it’s a really small amount and they’re troublesome to detect, this is likely to be dismissed as contamination: In workshops, artists used many various issues, and possibly the eggs had been simply from the tempera.”

Nevertheless, as a result of including egg yolk had such fascinating results on oil paint, the presence of proteins within the work is likely to be a sign of deliberate use as an alternative, the research urged. Ranquet hopes that these preliminary findings may appeal to extra curiosity towards this understudied matter.

Maria Perla Colombini, a professor of analytical chemistry on the College of Pisa in Italy, who was not concerned within the research, agreed. “This thrilling paper gives a brand new state of affairs for the understanding of outdated portray strategies,” she stated in an e-mail.

“The analysis group, reporting outcomes from molecular degree as much as a macroscopic scale, contributes to a brand new information in the usage of egg yolk and oil binders. They don’t seem to be extra merely figuring out the supplies utilized by Outdated Masters however clarify how they may produce great and glittering results by using and mixing the few accessible pure supplies. They attempt to uncover the secrets and techniques of outdated recipes of which little or nothing is written,” she added.

“This new information contributes not solely to a greater conservation and preservation of artworks but additionally to a greater comprehension of artwork historical past.”

High picture: The “Mona Lisa” by Leonardo Da Vinci

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