Scientists establish secret ingredient in Leonardo da Vinci work

Editor’s Observe: Join CNN’s Marvel Principle science e-newsletter. Discover the universe with information on fascinating discoveries, scientific developments and extra.

CNN
 — 

“Previous Masters” equivalent to Leonardo da Vinci, Sandro Botticelli and Rembrandt might 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 have been typically ascribed to contamination. A new research revealed Tuesday within the journal Nature Communications discovered the inclusion was possible intentional — and sheds gentle on the technical data of the Previous Masters, essentially the most expert European painters of the sixteenth, seventeenth, or early 18th century, and the best way they ready their paints.

“There are only a few written sources about this and no scientific work has been performed earlier than to analyze the topic in such depth,” mentioned research creator Ophélie Ranquet of the Institute of Mechanical Course of Engineering and Mechanics on the Karlsruhe Institute of Expertise in Germany, in a telephone interview. “Our outcomes present that even with a really small quantity of egg yolk, you possibly can 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 clean 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 a substitute of water, additionally has drawbacks, together with being extra vulnerable to paint darkening and injury attributable to publicity to gentle.

As a result of making paint was an artisanal and experimental course of, it’s attainable that the Previous Masters might need added egg yolk, a well-known ingredient, to the newer kind 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 substances — egg yolk, distilled water, linseed oil and pigment — to combine two traditionally standard and vital colours, lead white and ultramarine blue.

“The addition of egg yolk is helpful as a result of it might tune the properties of those paints in a drastic manner,” Ranquet mentioned, “For instance by exhibiting growing old otherwise: 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 instantly have an effect on the paint’s conduct and viscosity. “For instance, the lead white pigment is sort of delicate to humidity, however if you happen to coat it with a protein layer, it makes it much more proof against it, making the paint fairly simple to use,” Ranquet mentioned.

“Then again, if you happen to needed one thing stiffer with out having so as to add a number of pigment, with a little bit of egg yolk you possibly can 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 — equivalent to lapis lazuli, which was used to make ultramarine blue — have been dearer than gold, in line with Ranquet.

A direct proof of the impact of egg yolk in oil paint, or lack thereof, could be seen in Leonardo da Vinci’s “Madonna of the Carnation,” one of many work noticed throughout the research. Presently 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 mentioned.

One motive for wrinkling could also be an inadequate amount of pigments within the paint, and the research has proven that this impact might be prevented with the addition of egg yolk: “That’s fairly wonderful as a result of you have got the same amount of pigment in your paint, however the presence of the egg yolk adjustments all the things.”

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

New understanding of the classics

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 parts.

“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 mentioned. “As a result of it’s a really small amount and they’re tough to detect, this could be dismissed as contamination: In workshops, artists used many alternative issues, and possibly the eggs have 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 could be a sign of deliberate use as a substitute, the research advised. Ranquet hopes that these preliminary findings would possibly 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 mentioned in an electronic mail.

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

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

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