Moving a Masterpiece, One Panel at a Time

Diego Rivera’s ‘Pan American Unity’ survives its journey from City College to SFMOMA.

The phalanx of workers are on edge as they stand before the 4,000-pound panel. They eye it nervously from beneath their hardhats, and their trepidation is understandable. This is the last of 10 pieces of Diego Rivera’s colossal fresco, Pan American Unity, arguably San Francisco’s greatest artwork of the 20th century.

The stakes are elevated further by the fact that this piece is certainly the most fragile of the set, which the workers have spent months moving from the 30-foot-high wall at City College of San Francisco — where it has been since 1961 — to SFMOMA. Moving the priceless 1940 mural has been an elaborate maneuver involving vibration-sensing monitors, precision cutting tools, ropes, and intricate rigging connected to a three-story crane. Should this piece fall or cleave due to some other stressor, the loss would reverberate through the art world and beyond.

“Quiet please,” lead rigger Esteban Granados tells the observers gathered to witness this moment on June 17. He needs to focus on communicating with the crane operator. Minutes later, as workers begin pussing the panel from its moorings and lowering it slowly to the ground, Granados utters the four words project organizers have been waiting to hear.

“Looking good,” Granados says. “That’s beautiful.”

Long Time Coming




These are words that people have used to describe the mural itself, but the superlatives can also be applied to the mural’s removal from inside CCSF’s aptly named Diego Rivera Theatre. It took years of planning, and months of testing on a duplicate wall and two duplicate panels, which engineers developed and subjected to dropping and other extreme conditions, but Pan American Unity is finally near the end of its long journey to SFMOMA, where it will live for the next two years before returning to City College in a new space in 2023.

“We tried to replicate everything that would happen here,” Miguel Michel, the removal’s engineering project manager, says as he stands with other workers overseeing the final panel’s removal. “For example, it’s much better to hold the panel from the bottom than the top. We tried holding it from two points on the top and it created a new crack.” 

In theory, Pan American Unity always was designed to be movable. In 1940, Rivera painted his elaborate scenes on 10 steel-framed cement panels that collectively weighed more than 30 tons but could — with proper planning — be taken apart, transported, and then reassembled as Rivera envisioned. The reality was far different. After Pan American Unity debuted on Treasure Island, for what was called the Golden Gate International Exposition, it was slated for a City College library designed by celebrated San Francisco architect Timothy Pflueger, who co-organized the Treasure Island exposition and was Rivera’s patron. But the start of World War II in 1941 interrupted Pflueger’s designs, and ultimately suspended the library’s construction. And when Pflueger died in 1946, Pan American Unity remained in storage at City College — until 1961, when the panels were oddly attached to an inside wall that became the Diego Rivera Theatre.

How oddly? 

When project staff began examining the wall in earnest, they found major challenges with everything from the original 1961 mortar that workers used to fill spaces within the wall, to the complete lack of “as-builts” — meaning there were no actual plans that detailed how workers had assembled and attached the fresco panels to the CCSF wall. In architectural terms, the absence of an as-built is a major transgression. It required project staff to spend even more time probing the mural’s outside wall to get to the inside mural, and even more time to figure out how to remove the 10 panels from their 12-inch-thick plaster-and-concrete backing. Too much pressure at any point along the way — whether it was drilling holes in the outside wall or attaching cables that would lift the panels away — could damage the mural, which in practical terms is likely valued at more than $100 million. 

“It never should have been put in there like this — as a portable mural that was permanently attached,” says Bryan Cain, general manager of Atthowe Fine Art Services, who along with the company’s staff moved the mural. “It’s the largest, well-intentioned mistake that I’ve ever seen. … It’s like a drum head made out of a very fragile, brittle substance that should not crack, but that is permanently stuck in a concrete wall. What could go wrong?” 

Nothing did go wrong in the month that it took to remove all the panels, but three days after the project team removed the last panel at CCSF, they faced another final step: Transporting the panel slowly across San Francisco’s roadways to SFMOMA, where another giant crane plucked it from a truck on Howard Street and — with the help of workers on the ground — lifted the panel over city power lines, and into the museum’s ground-floor Roberts Family Gallery.

It is there that Pan American Unity will debut to the public in its new form on June 28. The ground-floor gallery is free to visit, so Pan American Unity will — 81 years after Rivera completed it — welcome visitors in a light-filled, art-specific venue that’s designed to bring out the mural’s best qualities, which are voluminous.

Broad Strokes 

Take, for example, its subject matter. The mural’s official title, in English, is The Marriage of the Artistic Expression of the North and of the South on this Continent. (In Spanish, it’s Unión de la Expresión Artística del Norte y Sur de este Continente.) Rivera gave himself license to represent every historical or then-modern facet of the Americas, whether it was the practices of Mayan and Aztec people, U.S. presidents like Abraham Lincoln, or the architectural doings of Pflueger (whose 140 New Montgomery building is just around the corner from SFMOMA).

Rivera put himself in the mural — along, of course, with Frida Kahlo, and a who’s who of other people he knew of or knew personally. He also added ominous figures and scenes from a world on the edge of war, as with the image of a white-hooded Joseph Stalin holding a bloody sickle, which referenced the then-recent killing of Rivera’s friend Leon Trotsky in Mexico.

Celebrated in his lifetime as Mexico’s most important muralist, Rivera created panoramic scenes that — like Michelangelo’s Sistine Chapel — unspooled layers of events and people into a single, epic vision. Rivera’s murals frequently highlighted everyday workers, indigenous people, and the ability of Communist or Socialist ideals to revolutionize societies. That’s what Rivera brought to Pan American Unity, which integrates similar themes with symbols of the United States’ technical and architectural advances from before 1940, as with the mural’s central figure, which combines the Aztec goddess Coatlicue with a Ford Motor Company stamping machine. 

As Rivera worked on the mural on Treasure Island, he saw Pan American Unity as a work that truly bridged epochs and people, according to the CCSF-backed Diego Rivera Mural Project. “It is about the marriage of the artistic expression of the North and of the South on this continent, that is all,” Rivera reportedly wrote. “I believe in order to make an American art, a real American art, this will be necessary, this blending of the art of the Indian, the Mexican, the Eskimo, with the kind of urge which makes the machine, the invention in the material side of life, which is also an artistic urge, the same urge primarily but in a different form of expression.”

Like Michel, who is a 25-year-old undergraduate student with the Mechanical Design and Technological Innovation Centre at the National Autonomous University of Mexico, key members of the project’s engineering team that moved the mural from CCSF to SFMOMA are from Mexico, and they say they feel a deeply personal connection to the mural’s themes — and the importance of bringing the mural to greater attention.  

“It was very emotional to see the mural,” says Alejandro Ramirez, who heads the project’s engineering team (and is Michel’s professor at the National Autonomous University of Mexico), as he recalled his initial 2018 impression and being asked to participate in the mural’s moving. “My mother is American and my father is Mexican, and when I looked at that mural, it was like the way that I had been taught. I said we would do whatever was possible to help on this project.”

Rivera’s America

Rivera died in 1957, but the themes he embedded in Pan American Unity are newly relevant at a time when politicians across the Americas debate policies around immigration to the United States, economic interdependencies among countries, and the indebtedness that each generation owes not just to those who came before but to those who will follow. To see a mural like Pan American Unity is to see the past but also the inextricable progress that cultures make. And the mural itself — its colorful pigments and its very materiality — is a reminder that the best art is always in need of care. For the month of July, visitors to SFMOMA will see conservators doing touch-ups and minor adjustments on Pan American Unity, just as visitors to Treasure Island in 1940 could witness Rivera undertaking his giant mural. (Next year, SFMOMA opens a major new exhibit called “Diego Rivera’s America.”) 

The fresco’s June 28 debut at SFMOMA will usher in an important new era for the work, says William Maynez, a longtime historian of Pan American Unity and a prominent member of the Diego Rivera Mural Project, who in 2010 initiated a study on how to move the mural from CCSF.

Standing inside the Roberts Family Gallery on June 20, as workers install the final panel on the wall, Maynez observes that Pan American Unity is on the verge of experiencing a public rebirth. He says the fresco’s SFMOMA relocation is a “coming-out party” that will put the work in front of more people “It’s finally going to get the exposure it merits,” he says.

At SFMOMA, a special steel support system stabilizes and locks the 10 panels in place. When Pan American Unity moves back to CCSF in 2023, to a new performing arts center, the mural will have a similar support system, and a much better viewing area for visitors, which the current Diego Rivera Theatre doesn’t have. The mural will never again be drilled into a wall, which means the next time the mural is moved shouldn’t involve so much sweat — either from physical exertion or from nerves.

Conservator Kiernan Graves, who is supervising the mural’s conservation, says Pan American Unity has gone through its share of “life trauma,” which resulted in what she calls, “minor delaminations, which means separation between plaster layers. There was some powder and pigment loss, and some cracks. But for what it has been through over the course of its life, relative to other portable frescoes by Rivera that had moved, this is certainly in the biggest and best condition.” 

In other words, visitors who see Pan American Unity at SFMOMA will see a work that looks much like it did when Rivera applied his pigments to wet plaster. He and his assistants had to finish each newly wet part in a single quick session. In the end, it took them four months to complete the giant fresco. It’s already lasted 81 years, and everyone who worked on the mural’s move — conservators, riggers, engineers, and others — says Pan American Unity should hold up well for at least 1,000 years. The key, they say: The mural has to be treated with kindness.

Jonathan Curiel is a contributing writer. Twitter @WriterJCuriel

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