Scientists determine secret ingredient in Leonardo da Vinci work

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“Previous Masters” comparable to Leonardo da Vinci, Sandro Botticelli and Rembrandt could have used proteins, particularly egg yolk, of their oil work, in keeping with a brand new examine.

Hint portions of protein residue have lengthy been detected in traditional oil work, although they have been usually ascribed to contamination. A new examine printed Tuesday within the journal Nature Communications discovered the inclusion was probably intentional — and sheds mild on the technical information of the Previous Masters, probably 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 executed earlier than to analyze the topic in such depth,” mentioned examine 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’ll be able to obtain an incredible change of properties within the oil paint, demonstrating the way it might need been useful for the artists.”

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

In contrast with the medium formulated by historical Egyptians known as tempera — which mixes egg yolk with powdered pigments and water — oil paint creates extra intense colours, permits for very clean colour transitions and dries far much less shortly, so it may be used for a number of days after its preparation. Nonetheless, 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 mild.

As a result of making paint was an artisanal and experimental course of, it’s doable that the Previous 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 examine, the researchers recreated the method of paint-making by utilizing 4 components — egg yolk, distilled water, linseed oil and pigment — to combine two traditionally widespread and important colours, lead white and ultramarine blue.

“The addition of egg yolk is helpful as a result of it will probably tune the properties of those paints in a drastic approach,” Ranquet mentioned, “For instance by displaying getting 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 immediately have an effect on the paint’s conduct and viscosity. “For instance, the lead white pigment is kind of delicate to humidity, however in case you coat it with a protein layer, it makes it much more proof against it, making the paint fairly simple to use,” Ranquet mentioned.

“However, in case you wished one thing stiffer with out having so as to add a number of pigment, with a little bit of egg yolk you’ll be able to create a excessive impasto paint,” she added, referring to a portray method 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 — comparable to lapis lazuli, which was used to make ultramarine blue — have been dearer than gold, in keeping with Ranquet.

A direct proof of the impact of egg yolk in oil paint, or lack thereof, might be seen in Leonardo da Vinci’s “Madonna of the Carnation,” one of many work noticed throughout the examine. Presently on show on the Alte Pinakothek in Munich, Germany, the work exhibits 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 purpose for wrinkling could also be an inadequate amount of pigments within the paint, and the examine has proven that this impact may very well be averted with the addition of egg yolk: “That’s fairly wonderful as a result of you’ve gotten the same amount of pigment in your paint, however the presence of the egg yolk modifications every thing.”

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

New understanding of the classics

One other portray noticed throughout the examine was “The Lamentation Over the Useless Christ,” by Botticelli, additionally on show on the Alte Pinakothek. The work is generally 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 mentioned. “As a result of it’s a really small amount and they’re tough to detect, this may be dismissed as contamination: In workshops, artists used many various issues, and possibly the eggs have been simply from the tempera.”

Nonetheless, as a result of including egg yolk had such fascinating results on oil paint, the presence of proteins within the work may be a sign of deliberate use as an alternative, the examine steered. Ranquet hopes that these preliminary findings would possibly entice extra curiosity towards this understudied subject.

Maria Perla Colombini, a professor of analytical chemistry on the College of Pisa in Italy, who was not concerned within the examine, agreed. “This thrilling paper gives a brand new state of affairs for the understanding of outdated portray methods,” 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 information 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 great 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 information contributes not solely to a greater conservation and preservation of artworks but in addition to a greater comprehension of artwork historical past.”

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