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What’s Inside Leonardo’s Palette: A Scientist’s Take on Historic Art Materials
- Bipasha Ray
- 2 days ago
- 6 min read
Painter, inventor, scientist, and visionary—one of the greatest intellectuals of all time, Leonardo da Vinci paintings and sculptures continues to shape and inspire the world as we know it. We think of Da Vinci as a master painter with near-impeccable application; we think of his many masterpieces: La Gioconda (Mona Lisa), Virgin of the Rocks, Last Supper, etc.
However, behind all of these works of art is another story involving chemistry, material sciences, and an excitement to experiment that is quintessentially Leonardo's. The revered artist's palette was better suited to be called a chemistry set, or a laboratory of art, rather than simply a toolbox.
Using advanced technology, including the likes of synchrotron X-ray imaging and molecular spectroscopy, scientists are now able to look inside Leonardo's paintings, and the discoveries are remarkable—the rarest of pigments, complex binders or fixatives, and a practice that sometimes bordered on recklessness.
Leonardo da Vinci's palette shows unparalleled artistic ability and a scientific curiosity that was never thwarted. This article documents what was really in Leonardo's palette by combining art history with scientific methodology to look inside the works he left behind.
A Scientist, Thinker, and Inventor in the Studio
Among Leonardo’s many anecdotal notes, he once wrote, "Painting is a science and all sciences are connected to painting." His belief in the inseparability of art and science is evident in the materials he chose. Unlike many of his contemporaries who depended upon the traditional recipes passed down through workshops, Leonardo worked with, changed, tested, and sometimes created new mixtures of colors.
Scientific studies show that he constantly stretched the boundaries of conventional practice. For example, while egg tempera and oil were the most common painting media in his time, Leonardo experimented with different mixtures of oil, resins, and even unconventional ingredients.
His notebooks are also filled with extensive notes on the behavior of pigments with different binders and how light strikes differently on surfaces and how paintings change visually with multiple layers of glazes over time. Leonardo Da Vinci’s experimental mindset turned his studio into a proto-scientific laboratory, where chemistry, optics, and mechanics could serve the purpose of painting.
Color as Chemistry
Leonardo's options for pigments were hardly limited. He selected a variety of minerals or derived from plant pigments, at least in part because they were both brilliant and permanent. Some of his sources of information are:
Lead White—lead corroded in the vapors of vinegar, and the most common white pigment used in Renaissance art; it could give opacity and coverage to his paints.
Vermilion—a brilliant red derived from mercury sulfide mineral known as cinnabar; it is toxic, but possessed such vivacity it was used without regard to its hazards.
Ultramarine—billed as one of the most expensive pigments available because it had to be extracted from lapis lazuli, mined in Afghanistan; The Madonna image of the Virgin of the Rocks demonstrated his privilege of using this color, but also his attempt to create the luminosity of the mineral's depth.
Ochres and Earth Colors—Iron oxides and clays produced warm yellows, browns, and reds, and allowed for an intense naturalistic flesh tones and backgrounds.
Azurite—a less expensive blue that provides many tonalities of the hue.
Carbon Black—made from charred organic material—is a great source of color for sketches and hatch/ shadows.
Ultimately, it wasn't merely the pigments he employed that made his compositions incredible; it was the way he applied and laid multiple layers of the pigments that added life to Leonardo da Vinci's palette.
The Binder Mystery
Pigments require a binder to mix with surfaces, and Leonardo's experiments with binders exhibit his scientific audacity. Traditional oil painters worked with linseed oil or walnut oil, each with its idiosyncratic drying times and effects. However, researchers confirmed that Leonardo contributed unconventional binder materials.
New studies of Leonardo da Vinci Mona Lisa painting and the Last Supper fresco provide traces of plumbonacrite, a rare lead compound that occurs when the oil was heated with lead oxide. Thus, this implies Leonardo may have purposely cooked the oil with lead oxide to form a thick, fast-drying medium. Although an abnormal practice, it would have allowed him to smooth out the blending of ethereal transitions between light and shadow, which is known as sfumato.
While Leonardo's experiments exposed him to potentially interesting binders, they sometimes created technical problems--like when he used mixtures of tempera and oil on dry plaster in The Last Supper instead of true fresco, which exacerbated the work's degradation, triggering boundless art restoration attempts over the centuries.
A Chemical Tour de Force
Leonardo's most famous innovation, sfumato, required not just artistry but also chemical skill. The process involved the use of ultra-thin glazes of paint, pigment suspended in oil, layered on a surface, to make the transitions of tones imperceptible, giving elusive softness to faces like Mona Lisa.
Analysis shows, generally, these glazes were less than a micron thick and involved a human labor-intensive process to deliver the optical effect. Patience is required because each layer was translucent and needed a proper dry time before the next layer could be applied.
From a scientific point of view, sfumato reveals Leonardo's knowledge of light and optical science, and the scattering of light onto surfaces simulating a thin haze in the atmosphere, not in abstraction, but rather at a microscopic level, emerging from the paint itself.
Leonardo da Vinci's Palette: Beneath the Masterpiece
The substrate to paintings, the canvas or panel beneath the paint, is as much a part of the artwork as the paint itself. Leonardo often painted on wooden panels (often made of poplar), but he also occasionally used canvas. They were prepared with what is called a ground. The ground was a mixture of gesso, white lead, or gypsum that created a smooth and reflective surface.
What is different is that Leonardo occasionally altered his ground with other materials. Using synchrotron radiation, analysis of some paintings revealed that certain works had manganese and lead-based additives in their ground. It is thought that these additives were used to vary drying times or saturated surface brightness. These alterations again illustrate his endless experimentation.
More than Drawing and Ink
Leonardo's genius was also evident in his drawing, where he even worked with silverpoint, charcoal, and ink. Studies of his notebooks show that he typically used iron gall ink, a combination of tannins (from oak galls), iron salts, and gum arabic. Iron gall ink degrades the paper over time, which is a current challenge for conservators today.
In his preparatory sketches, he employed layers similar to his painting technique, starting with light constructions using either chalk or metal point, detailing the contours with ink, and shading with hatching and washes. These methods exemplify the consistency between his drawing and painting: both were processes of building up layers that mimic our perception of light passing through layers.
Modern Science Looks Back
Many of these discoveries are recent. They were made possible by advanced imaging and chemical analysis. Researchers can now see under paintings, using techniques such as X-ray diffraction, synchrotron X-ray fluorescence, and infrared reflectography, without damaging the paint layers.
At the European Synchrotron Radiation Facility (ESRF), scientists detected the presence of plumbonacrite in the Mona Lisa, a compound that rarely occurs in Renaissance paintings. The discovery indicates not only that Leonardo did indeed "experiment" with experimental binder recipes but also the working timeline for his paint, since these mixtures would dry differently than oils.
The chemical analysis done recently of the Virgin of the Rocks revealed the use of rare mineral-based pigment and sophisticated layering approaches. Each new finding has made it more difficult to view Leonardo not simply as an artist but as a pioneer of materials science.
Why Leonardo's Art Materials Matter Today
Leonardo is relevant and enduring not only because of the beauty of his art, but also because it represents a dialectic between human creativity and inquiry. Leonardo's palette never represented a "fixed" subject of study, but rather a dynamic space of experimentation and discovery. For today's scientists, the expression of authenticity in Leonardo's materials extends beyond art history; this includes the historical record of the practice of chemistry, the invention of optics, and the principles behind engineering materials.
Furthermore, studying Leonardo's materials can help to do more than trace one of the pasts’ stories. Identifying substances that cause instability or discoloration can help conservators to preserve their work for future generations.
In many ways, Leonardo da Vinci's palette embodies the spirit of the Italian Renaissance: the convergence of art and science. Leonardo has much to teach us about innovation, requiring an audacity to question the established conventions of today, a willingness to experiment even at the risk of failure.
In Retrospect
In essence, Leonardo da Vinci's palette is akin to opening a Renaissance science time capsule. Every pigment, binder, and layer contributes to the tale of a mind that resisted boundaries between fields of study. He was both a chemist and a painter. He was both an inventor and an artist.
Whether it is the smile of the Mona Lisa, the gaze of the Virgin of the Rocks, La Mundi, or the diminishing brilliance of The Last Supper, it is ingrained with remnants from experiments carried out 500 years earlier. Now that scientists are beginning to understand these enigmas with modern machinery and expertise, Leonardo endures not only through his paintings but also within the historical study of art and science.
