Uncovering Hidden Colors in Historical Works of Art
“Irises” by Vincent van Gogh contains hidden “fugitive pigments” that have faded with time. (The Metropolitan Museum of Art/Public Domain)
You may not know it by glancing at his paintings today, but Vincent van Gogh had a thing for a vivid scarlet pigment known as “geranium lake.” The challenge with this vibrant red is that it’s what art conservators call a “fugitive color,” a pigment that fades easily with environmental exposure. From early cave paintings to masterpieces by 19 th century artists like van Gogh, pigments in works of art commonly break down chemically over time.
But today, thanks to the collective efforts of art conservators, museum scientists and chemists, it’s once again possible to see the vibrant hues of historical works of art in their full-spectrum of color.
“Advances in modern chemistry are greatly paving the way for a new era of art restoration,” says Dr. Heino Heckmann, Head of Global Technical and Strategic Marketing, Special Applications, Business Unit Pigments .“Today’s chemists are improving our understanding of the fate of historical pigments and developing advanced analysis tools to uncover art’s mysteries of the past,” he says.
At the Metropolitan Museum of Art in New York, Marco Leona, head of their Department of Scientific Research, is using high-tech analysis to uncover the presence of long- faded “red lake” pigments in van Gogh’s works. These pigments are derived from the synthetic dye eosin, commonly used in medical research for tissue staining. Because eosin contains the element bromine, rarely found in pigments, researchers can use an advanced chemical mapping tool known as x-ray fluorescence spectroscopy imaging to detect the presence of the reddish-brown element, without harming the painting. “It’s a very powerful technique, just a handful of museums have the capability to do this,” Leona said in a recent “Chemistry World” article.
"Advances in modern chemistry are paving the way for a new era of art restoration."
Art conservators have no intention of re-painting these great masterpieces, which is frowned upon in the art world. Instead, they’re turning to a strategy known as “digital restoration.” In the Met’s 2015 van Gogh exhibit “Irises and Roses,” Silvia Centeno used advanced chemical analysis to map the fading of red lake pigments in the spring flower still-life series. Using this data and historical records, Centeno was able to re-produce digital color simulations that showcased these classic works with a close approximation of how van Gogh intended them to appear.
Finding Traces of a Pigment Fit for the Gods
Ancient Egyptian blue, also known as calcium copper silicate, is believed to be the first artificial pigment ever made. was found in Egyptian tombs as early as 3,200 B.C. depicting the color of the heavens and gods. The pigment was also used in later periods by the Romans and Greeks, and traces of it have been found in the Parthenon’s sculptures.
As a result of new imaging technology, researchers at the British Museum in London, have been able to uncover traces of this synthetic pigment on a range of objects from the ancient Egyptian to Roman periods. Not only used as a blue pigment, scientists believe the ancient paint was used in mixtures with other colors to brighten objects. And thanks to the discovery that this pigment can be detected with infrared light, the museum’s scientists have developed a non-invasive technique, called visible-induced infrared luminescence (VIL), to find traces of hidden color on a variety of ancient sculptures and statues. With these scientific advances, once-monochromatic historical art is returning to its full-spectrum glory.
And as we look into the future, science will continue to be an important partner in art. “Modern artists today have the benefit of a broader palette of possibilities to choose from when creating works of art - high-performance pigments that are more longer-lasting and durable will enhance timelessness,” says Heckmann.