O’Keeffe herself saw the damaging effects of pin-sized, blister-like protrusions forming on her work back in the 1940s.
According to Dale Kronkright, head of conservation at the O’Keeffe Museum in Santa Fe, correspondence between the artist and her then-conservator Caroline Keck indicates her concern about the 1928 painting “Calla Lilies On Red.” It needed to be fixed and re-painted in small areas to match the colors that had popped off or dissolved over time.
“The chemistry then just wasn’t as easy,” said Kronkright. “So (Keck) didn’t know what was going on and why the paint was popping off.”
For a while back in the 1990s and early 2000s, he said, scholars assumed the tiny bumps were sand that O’Keeffe must have added to her paint, for texture, while famously working in the northern New Mexico desert around her home in Abiquiu.
Kronkright noticed the same problem on paintings in the O’Keeffe Museum around 2001 and began studying them thoroughly in 2011, using 3-D imaging. He now knows the protrusions are the result of deterioration caused when damaging “soaps” form as certain materials used in O’Keeffe’s paint react with each other.
Kronkright and other conservationists from the Georgia O’Keeffe Museum, along with scientists from Northwestern University and the Art Institute of Chicago, are now teaming up to help fight the damaging soaps – soap in this case referring to a particular chemical mix.
Recently, the partnership received a nearly $350,000 grant to improve technology that can determine what occurs within a painting over a given period of time and in turn provide a better understanding of what conservation measures might help or hurt.
According to an announcement last week, the National Endowment for the Humanities grant will allow for improved development of 3-D imaging technology to monitor the rate of growth – both in quantity and size – of soaps in a painting.
The technology is vital, according to Kronkright, because it makes it possible for scientists to effectively keep up with changes to a painting without physically touching it.
Otherwise, “what you’d have to be able to do is take a painting, count and measure thousands of (soap-caused protrusions) … and then measure them under the microscope and check again in five years,” he said.
The soaps, which rise and can reach the diameter of a few hairs, cause major discoloration and darkening or force pieces of paint to come off entirely. They can form when synthetic fats used in oil paint combine with alkaline materials like pigments.
About five O’Keeffe paintings have required repairs due to significant soap damage, but Kronkright said about 95 percent of the collection’s artwork shows some evidence of it.
And, he said, “This is a worldwide problem.” Kronkright estimates about 70 percent of all art collections may be affected.
Soaps have been detected in artwork made as early as the Renaissance. But the majority at risk are 20th-century oil paintings.
In 1920, paint companies began adding a synthetic fat, aluminum stearate, to keep pigments and oil from separating in the tube. On a canvas, the fat can flow “like liquid” and form soap when it bonds with substances like pigments.
Because it can affect collections everywhere, Kronkright said the eventual goal of the project funded by the NEH is to create an online system where conservators can send images of affected paintings and share how the images may be providing information about mitigation techniques.
Kronkright said the museum already has some ideas about what accelerates soap formations, but currently there isn’t an efficient way to test the theories.
Museum personnel have started using frames that control moisture content as one possible soap inhibitor. Also, they believe there may be correlations between soap formations and what types of paints were used, as well as how often a painting travels, because high temperatures or fluctuating humidity might accelerate the unwanted chemical reactions.
“These are the kind of things we’ve been guessing at, but the new project will be able to confirm and quantify,” Kronkright said.
The project, titled “Metallic Soap Protrusions on Georgia O’Keeffe’s Paintings: A Methodology to Diagnose Morphological and Chemical Changes,” will start this spring.