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For the de Young Museum, It’s Not That Easy Being Green

Is climate change, the drought, or something else to blame for the museum’s extra-slow change in hue?

Top: An artist’s rendering of the de Young at the time of construction. Bottom: The initial 15-year projection.

Editor’s Note: This is one of many stories about Golden Gate Park that San Francisco is publishing over the next month as part of the June 2017 issue. To read stories as they become available online, click here.

When the de Young Museum
, formerly a flamingo-pink Spanish colonial, was formally reopened in October 2005 as a sleek, angular fortress, Swiss architects Jacques Herzog and Pierre de Meuron declared that their inspiration for the building had come from the very park that surrounds it. “Nature, trees, plants, and water, in various forms, are an integral part of the building,” reads their website’s description of the museum. Jayne Barlow, who managed the build, told KQED radio upon the opening, “Basically, we see the museum as an extension of a walk you might take through the park.”

But the most spectacular fusion of environment and structure would take time. Over the coming 15 years, the copper paneling encircling the 293,000-square-foot building were meant to oxidize and take on a green hue—the same phenomenon that happens to old pennies. Eventually, the building would come to blend in with the trees and foliage around it.

Twelve years later, you’d be hard-pressed to call the joint green, exactly. Rather, it’s darkened to a deep-rust color and is only streaked with green—mostly on the building’s northern face, where the gutter system channels rainfall runoff. Says Francisco Rosas, a communications staffer with the museum, “A lot of the oxidation relies on the thick marine layer—including the fog and the rainfall.” And suffice it to say, until this past winter, San Francisco has had less of that than usual. In fact, the city’s famed fog has been in decline for years, according to UC Berkeley researchers.

Still, rather than chalking up our ungreen museum as another casualty of climate change, take heart: The big change will indeed come—eventually. Bill Zahner, whose company fabricated the 950,000 pounds of copper used in the de Young’s construction—perforated and dimpled to resemble columns of light radiating through the treetop canopy—says he expects the greening to take another decade or so, and perhaps 50 years to get as bright as the Statue of Liberty. 

And that’s not just because of a lack of rain. Zahner explains that oxidation occurs when copper comes into contact with pollutants in the air, particularly carbon dioxide, sulfur, and chlorine. (The wet spots oxidize faster because rainwater has electrolytes in it and tends to carry pollutants.) Those join with the copper to form minerals on the surface of the metal—copper carbonate, copper sulfate, and copper chloride—that are trapped there permanently, creating the distinctive hue. But 21st-century San Francisco has a lot less sulfur floating around in the air than 19th-century New York did. Less pollution in the atmosphere, in this case, means less green on the de Young.

In the meantime, revel in the building’s unique patina. “I was out there recently, and I thought the color was richer than any surface I can think of,” Zahner says. “It’s almost like leather. And it does that just simply because it’s in Golden Gate Park, a place on earth with its own specific environment.”


Originally published in the June issue of San Francisco

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