Living Artwork

Andy Warhol died over 37 years ago, yet one of his artworks continues to evolve. It’s a chemical-reaction marvel of a painting, made in 1978 and among the largest pieces in Andy Warhol’s Oxidation series at just over 4 feet by 16 1/2 feet. The concept behind the series is simple: when dripped and dribbled with urine, metallic paint-coated canvases develop abstract images as the uric acid oxidizes. 

But without intervention, the scientific phenomenon that created Oxidation may be its undoing. In 2020, staff at The Andy Warhol Museum discovered mysterious puddles below the painting and a new drip pattern on its surface. It was as if the chemical reaction that produced the artwork had been reactivated.

The conservator at The Warhol, in collaboration with mineralogists and forensic scientists, is searching for clues as to how to stop or even reverse Oxidation’s changes. Their work is documented in an exhibition on view through the end of 2024 called Altered States.

Ironically, none of this would surprise Warhol himself. In a 1985 interview with art historian Benjamin Buchloh, Warhol described how paintings in his Oxidation series melted under the hot lights when exhibited at the Paris Art Fair FIAC at the Grand Palais, even likening them to religious iconography.

“They never stopped dripping because the lights were so hot. Then you can understand why those holy pictures cry all the time—it must have something to do with the material they were painted on or something like that,” he remarked, seemingly unfazed.

While Warhol signaled his acquiescence to the painting’s degradation, that kind of change shouldn’t happen under The Warhol’s stewardship, says Rikke Foulke, associate conservator of paintings.

Photo: Bryan Conley

“If we continue to let Oxidation drip, we may not have a painting for the next generation,” she added.

The popularity of the painting, made by a man credited with declaring, “In the future, everybody will be world-famous for 15 minutes,” has connected with a younger generation of art lovers on apps like TikTok, the social media platform known for short-form videos. A 30-second TikTok video about Oxidation—which was produced by The Warhol—has garnered 63,000 likes and more than 700 comments.

What’s apparent in the TikTok discourse regarding Warhol’s artistic output and Oxidation touches on what has endeared his work for generations: Warhol challenges the very concept of what can be defined as art and who can consider himself an artist. 

“Why don’t they teach this stuff at school?” says one commenter. “I definitely would have become an artist.”

Groundbreaking Conservation

It was the summer of 2020 when staff members at The Warhol first saw the stains under Oxidation, a line of coffee-colored, circle-shaped drops and a larger splotch in the shape of West Virginia below the painting’s right corner. After they notified Amber Morgan, director of collections and exhibitions, she went over to the painting to see if there was a ceiling leak.

There wasn’t. 

Identifying the source of a problem with a piece of art is rarely that easy, Morgan says. For almost 25 years, she’s managed artworks at The Warhol and Carnegie Museum of Art and has seen her share of issues. 

“Generally, artists don’t think of preservation when creating work; they will make what they’re going to make,” she notes. 

Carnegie Museums staff are trained to handle collection-related emergencies and the initial steps are fairly straightforward, even if the ultimate solution is not. First, document the conditions of the affected artwork. Next, examine the rest of the collections for signs of damage or impending damage. Finally, determine the next steps to prevent future issues.

Many materials popular in modern artwork—not just artwork made with urine—suffer from an inherent vice: disintegration due to their inborn characteristics. 

“It can be infuriating as a museum person to think, ‘What is the future of this object?’” Morgan says. “One example:  Art made with newsprint is difficult to preserve because it is made of the cheapest pulp paper and becomes yellow and brittle when it ages. Art made with pantyhose, with rubber tires—it’s all going to deteriorate.” 

And therein lies the challenge for Foulke and her colleagues: How much of what’s happening to Oxidation is inherent vice? How can the painting’s degradation be slowed down, stopped, or even reversed? 

Photo: Bryan Conley

With a generous Bank of America Art Conservation Project grant, Foulke and her peers are performing groundbreaking research to uncover the answers. Visitors to Altered States can view the clues Foulke and her team are following in their quest to uncover the mysteries within Oxidation. On display are mock-up canvases created by Warhol staff, canisters of metallic flakes used by Warhol in his series, and sample minerals—on loan from Carnegie Museum of Natural History—that were used in the making of ancient pigments. 

“Altered States is a showcase of how conservation overlaps with art, history, chemistry, and minerals,” Foulke says.

Their findings will inform critical conservation work of The Warhol’s Oxidation series holdings and additional Oxidation paintings in public and private collections.

Foray into the Abstract

Warhol’s Oxidation series is a major departure from his groundbreaking Pop art screen prints. Those images, easily replicated and mass produced, spotlight the aesthetics of everyday objects and celebrity publicity shots. However, the paintings that make up the Oxidation series challenge viewers to take a closer look at a commonplace sight—oxidation is everywhere, from rust on car doors to the green fuzz on old pennies.

The paintings in the Oxidation series are Warhol’s first foray into abstract expressionism and are believed to be inspired by Jackson Pollock’s work—paintings resembling scribble-scrabble drips and splashes of paint. The places where urine blotched and mottled the canvas contain green, blue, and charcoal hues—vivid, large-scale rust spots made into art.

Warhol was an artist of high concept, even if his execution appeared simple. Creating paintings through chemical reactions takes dedicated study, intentionality, and experimentation. 

The work may appear random to an uninitiated viewer, but Warhol took great care when creating the Oxidation paintings, says Foulke.

In creating the paintings, Warhol and his assistants mixed together dry metallic powder with water and an acrylic binder. They then laid the canvases on the floor, coated them in copper paint, and urinated on them while the paint was still wet. The chemicals in the urine reacted with the metal substrate, producing oxides that create unique patterns.

Photo: Bryan Conley

Foulke notes that the people who contributed urine to the series—Warhol’s friends and associates—even adopted an experimental vitamin regime to determine whether the chemicals present in their urine could influence the colors that emerged when applied to the treated canvases.  

Longtime Warhol collaborator and Factory member Ronnie Cutrone mentioned the method in a 1998 interview with gallerist Daniel Blau.

“They [the paintings in the Oxidation series] are just scientific experiments. The first chemical was B complex, which we put into our urine,” he told Blau.

“Warhol pointed out that a person can’t just go and urinate on a canvas expecting the result to be interesting. A contributor must develop their skills for a successful composition,” says Foulke. “Warhol would view the results and cut up canvases into individual pieces to distinguish the most interesting parts,” she adds.

Cross-Disciplinary Analysis

To understand how and why Oxidation came to evolve more than 40 years after it was painted, Foulke started at the birth of the painting. Following Warhol’s protocol, she recreated the Oxidation series.

The Warhol Museum Archive is the most extensive collection of Warhol ephemera in existence—more than 8,000 cubic feet of material housing half a million objects, including notebooks, sculptures, audio tapes, and canisters of the metallic powder used in the Oxidation series, and scraps cut from the Oxidation canvases from when they were stretched onto frames.

The Warhol’s archive and recorded interviews with Warhol’s Factory assistant Ronnie Cutrone were integral to producing mock-ups of the Oxidation series. Using a recipe documented by Cutrone, Foulke mixed metallic powder with water and acrylic paint and applied it to several canvases. Then, using a pipette, Foulke applied urine donated by The Warhol’s staff to the canvas. 

The mock-ups and scraps were delivered to two of The Warhol’s partners for analysis: Carnegie Museum of Natural History and RJ Lee Group, an industrial forensics analytical laboratory and scientific consulting firm.

Foulke tapped Travis Olds, assistant curator of minerals at the Museum of Natural History, to learn about the mineral-based pigments in Oxidation. Warhol was hardly the first artist to use urine in the composition of an artwork. Notably, Pliny the Elder, a first century A.D. scholar interested in minerals, recorded a recipe for verdigris, a blueish-green pigment using copper and urine. 

“So many materials, like the paint and the metal that goes into art, are mineral-derived; a mineralogist can lend insight into the history of an artwork,” Olds explains.

Stewardship of The Warhol’s collection has long benefited from the experts of the Museum of Natural History, including entomologists who support The Warhol’s integrated pest management program and taxidermists who help maintain and preserve the stuffed lion and stuffed dog, Cecil, in the museum’s collection.

“Working with artists and conservators that think and approach problems differently than me is fun,” says Olds. “They bring a new perspective, and we make a great team to try and fix them.” 

During his tenure at the Museum of Natural History, Olds has consulted on multiple art conservation projects, including the impact of fingerprints on Meg Webster’s sculpture, Nose Cone, a stainless steel conic cylinder at Carnegie Museum of Art. He has also helped recreate an ancient pigment whose recipe was believed to have been lost to history—the vibrant “Egyptian blue.”

“As a mineralogist, I characterize materials,” Olds explains. “I want to understand what’s in them, what atoms are there, how much of each atom, and then how they’re arranged. Once you know that, you know so much about the material.”

With Oxidation, Olds used a scanning electron microscope to capture an image of the paint 100 microns in size, about the width of the strand of hair. Electron microscopy is a unique type of microscopy in that it uses electrons to look at the surfaces of objects and their composition.

He wanted to know more about the composition of the paint and, to use an unscientific word, the “goo” that formed on the canvas when it dripped. Olds describes the goo as the “organic junk left after the urine degraded and mingled.”

He found that the samples contained a medley of elements, including copper, potassium, carbon, oxygen, chlorine, and sodium. 

“When I see things like sodium, potassium, and chlorine in a sample, my mind goes to salt. And, of course, urine has a large salt content,” says Olds. 

For Olds, the presence of salt is a red flag to understanding why Oxidation began deteriorating—some salts like to absorb water from the air. As for the goo, it contains copper, but it needs further analysis to determine its other components, he says.

Unlocking Mysteries

Another clue to unlocking the transformation of Oxidation lies in The Warhol’s HVAC data. In the days before the drips were discovered below the painting, the HVAC system suffered a mechanical failure that caused it to go offline for a few hours. The museum’s climate dramatically changed, creating what Foulke describes as a perfect storm: The humidity and temperature in the gallery rose; when the climate control system returned online, the air cooled and released moisture, triggering Oxidation’s chemical reaction.

The forensic scientists behind RJ Lee Group, whose labs are in Monroeville, Pennsylvania, have extensive experience recreating atmospheric conditions. The company consults for a diverse clientele, from casino owners concerned about the integrity of their keno balls to manufacturers who want to understand why their product unexpectedly broke.

One avenue of analysis they’re pursuing to learn about the changes exhibited by Oxidation is subjecting the scraps and mock-ups to an accelerated aging process. They can recreate the temperature and humidity conditions in the gallery the day the HVAC system went offline and even process the samples to see how 50 years of aging will impact the painting.

To do this, the scientists place specimens in an aging chamber resembling a large refrigerator with racks inside, and then subject them to atmospheric extremes that alter the chamber’s temperature and moisture level.

“If we continue to let Oxidation drip, we may not have a painting for the next generation.“

Rikke Foulke, The Warhol’s associate conservator of paintings

Scientists also attempt to understand the chemistry that created Oxidation’s colors.

“We’re talking about chemical reactions that are not really controlled,” says Chris Hefferan, an applied physicist and consulting scientist. “Warhol and his associates knew that if brass met urine, it would create a color effect. But there are subtleties in the colors resulting from a spectrum of compounds present in the artwork. We weren’t expecting that. 

“I think the complexity of it has been the most surprising on my end; we’re still kind of feeling our way through it. There are continuous variables to consider,” he adds.

In the coming months, the RJ Lee team plans to analyze cross sections of the samples—that is, the thinnest edge of the samples. In theory, this approach will help them better analyze the paint material separate from the canvas.

“We think that by viewing a cross section, we’ll see the salts on top of the colors produced by the urine separate  from the acrylic-metallic paint layer,” says Hefferan.

“If I were to analyze a Rembrandt or Picasso, I would be working with pigments based upon a specific set of minerals; we know what we expect to see in the red paint on those artists’ paintings,” Hefferan adds. “With Oxidation, we’re still trying to understand the chemistry that creates the colors. Once we understand the chemical reactions behind those pigments, we can use that characterization to understand what might happen in other circumstances.”

It’s unclear how much longer this work will take. The results from RJ Lee could lead to other avenues for investigation, Morgan notes. Regardless of how long it takes, she and Foulke hope this research is useful for conserving Oxidation paintings in other collections.

Foulke also recognizes an inherent contradiction in conserving Oxidation. As stewards of the collection, The Warhol needs to make sure the paintings are around for generations to come. But they also need to honor the artist’s intention.

“I’m not sure if there is a treatment we can do [to prevent further changes]. I’m not sure that there is a treatment we want to do,” Foulke says. “[Warhol] accepted this as change. And I can accept damage to some extent, but I don’t want the painting to—to use his words—melt away before our eyes.” 

Funding for the conservation of this artwork was generously provided through a grant from the Bank of America Art Conservation Project.