Diagnose acne art in Georgia O 'Keeffe's paintings


A detailed section of & # 39; Pedernal & # 39; shows near protuberances the size of a micron from metallic soaps.Georgia O 'Keeffe. Pedernal, 1941. Oil on canvas, 19 x 30 1/4 inches. Georgia O 'Keeffe Museum. Gift of the Georgia O 'Keeffe Foundation. © Georgia O & # 39; Keeffe Museum. [2006.5.172] Credit: Dale Kronkright / Georgia O Keeffe Museum

Even Georgia O 'Keeffe noticed that pin-sized blisters bubbled on the surface of her paintings. For decades, ecologists and specialists have speculated that these tiny protuberances were grains of sand from the New Mexico desert, where O & # 39; Keeffe lived and worked. But as the protrusions began to grow, spread, and eventually flake off, people went from curious to worried.

A multidisciplinary team from Northwestern University and Georgia's Keefe Museum in Santa Fe, New Mexico, has now diagnosed the odd disease of painting: protrusions the size of a micron are metallic soaps, resulting from a chemical reaction between metal ions and fatty acids commonly used as a binder in paints.

Inspired by research, the team has developed a new portable tool that can easily map and monitor works of art. This tool allows researchers to carefully observe the protuberances to better understand the conditions in which they develop, contract or burst.

"The free fatty acids in the paint binder react with lead and zinc pigments," said Marc Walton, professor of materials science and engineering at Northwestern's McCormick School of Engineering, who led l & # 39; study. "These metal soaps have begun to aggregate, repel the surface of the paint and form something that looks like acne."

"If we can easily measure, characterize and document these soap protuberances without much cost to the museum, we can watch them grow," said Oliver Cossairt, an associate professor of computer science at McCormick, who led the development of technology. "This could help conservatives diagnose health and prescribe treatment options for damaged artwork."

Walton, co-director of the Center for Science Studies in the Arts, a collaboration between Northwestern and the Art Institute of Chicago, will discuss research and technology results at a press conference on February 16 at the American Association for the Advancement of Science (AAAS) annual meeting in Washington, DC

The information session entitled "Art Conservation Builds on Advanced Scientific Know-How" will be held at 9:00 am EST on Balcony A at Marriott Wardman Park.

Cossairt will present the research at a scientific session the next day. Her presentation, "Diagnosing a Painting Illness with Computer Science: The Case of Georgia O. Keefe", is part of the session "Medicine, Computer Science and Art: Learning Through Technology" (8am to 9:30 am EST Feb. 17, Ward 2, Marriott Wardman Park).

Oliver Cossairt, a professor at Northwestern University, brings together the surface metrology of Georgia's "Ritz Tower" painting with a handheld device. Credit: Northwestern University

The AAAS Scientific Session is curated by Francesca Casadio, Executive Director of Grainger for Conservation and Science at the Art Institute and Co-Director of the Center for Scientific Studies on the Arts.

Dangerous disease

Almost all Georgia O 'Keeffe paints have suffered some degree of damage due to the formation of metallic soap. Some of the cases of acne are in an early stage of development and can only be seen in ultraviolet imaging, but others are more advanced and can be seen at the naked eye. The curators have restored some of the paintings where the damage is more pronounced, but the protrusions continue to return.

"The rate of deterioration is one of the most important issues in the study," said Dale Kronkright, head of conservation at the Georgia O 'Keeffe Museum. "There seems to be a correlation between the number of times that paintings have been visited by public exhibits and the size and maturity of the surface disturbance.The more paintings have traveled, the greater the likelihood that protrusions will be bigger and larger. many, many. "

Walton and his team at the Center for Scientific Studies of the Arts are studying the speed with which the process can advance by inducing a deterioration of metallic soap in substitute paints. They also possess decades of detailed information from the Georgia O 'Keeffe Museum, which documents the different environments that different pieces have experienced during their travels and their exhibitions.

"Once we understand what environmental conditions they were in, what kind of relative humidity, what kind of temperatures, what they were exposed to in direct sunlight, then we can prescribe an environment. especially with special conditions that will allow the artwork to survive for a very long time, "Walton said.

These findings can also be applied more broadly beyond O & # 39; Keeffe's masterpieces. Soap protrusions damage oil paints of all eras.

"If we can solve this problem, we are preserving our cultural heritage for future generations," Walton said.

From science fiction to non-fiction

Cossairt compares his portable tool to a Star Trek "tricorder". Fans of the series will remember watching their favorite characters use the handheld device to spot unknown areas, examine inanimate objects and diagnose an illness.

Instead of assessing the health of a human being (or an alien), the tool developed in Cossairt's lab can help diagnose the health of a painting. It uses the LCD screen and the camera already available on smartphones and tablets. With a simple wave on the surface of a painting, the application quickly digests the precise three-dimensional surface structure of the work, or metrology. He can then subtract the color from the work to help the researchers identify any deviation in the shape of the surface that does not come from the brushstrokes or texture of the canvas.

"It's like the" tricorder "measurement tools," said Cossairt. "This can give you extremely accurate measurements, but it's also something you can just get out of your pocket."

The application uses the light source of a mobile device (LED flash or LCD screen) to reflect light on the surface of the paint and capture these reflections with the camera. The image is then processed by custom algorithms developed by Aggelos Katsaggelos at Northwestern to extract the surface shape information.

"We collect a lot of data in an effective and successful way, but then we have to treat it," said Katsaggelos, professor of electrical engineering and computer science at McCormick University, Joseph Cummings. "The technology uses machine learning to distinguish whether the texture is a soap protrusion or something as benign as a brushstroke, and then, for projections, we extract statistics – density, size, and shape. . "

Compare this handheld device to the large, bulky equipment that is currently needed to map the metrology of a painting. The main technique, called reflectance transformation imaging, requires a large dome composed of multiple light sources and a costly configuration. Few museums can invest in the purchase and maintenance of such instruments.

"We are trying to make it much simpler, much cheaper and more readily available to reduce barriers to use," Cossairt said.

The research is funded by the National Endowment for the Humanities.

Explore further:
Experts Try to Prevent Discoloration of Georgia O 'Keeffe's Paintings

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