Victor Arnautoff didn’t just paint the kaleidoscopic mural “City Life” inside of Coit Tower and move on. There was a class struggle to fight, so Arnautoff followed his tower work with a brilliant wall painting of port workers in Richmond for that city’s main post office.

Nobody remembers “Richmond: Industrial City,” because it disappeared in 1976 when the post office was remodeled and the 13-foot painting was rolled up for storage. Presumed lost, it has miraculously resurfaced and will get its gallery debut Sept. 13 in the labor archives at San Francisco State University.

The painting is the centerpiece of the first American career retrospective on the working-class art of Arnautoff, a Russian-born social realist who fled his home country during the Russian Revolution, found his way to San Francisco as an art student, and ended up as one of the most influential public works painters during the New Deal.

The exhibit, titled “Victor Arnautoff and the Politics of Art,” includes block prints from the San Francisco General Strike in 1934 and smaller reproductions of his mural of George Washington as a slave owner, installed at Washington High School in 1936, along with his Coit Tower work from 1934.

“Richmond: Industrial City,” is the only piece that is full-size, 6 feet by 13 feet, and it, too, is a reproduction because the original remains in storage and is too fragile for display.

San Francisco State history Professor Emeritus Robert Cherny, who may be the world’s foremost Arnautoff expert and wrote the book, “Victor Arnautoff and the Politics of Art,” on which this show is based, had never seen the original in anything larger than a photograph before he came by the Labor Archives and Research Center in the new campus library.

“It’s much more impressive full-size than on a computer screen, which is all I had ever seen of it,” says Cherny, who curated the exhibit. “Seen full-size it is quite spectacular and his use of color is strikingly vivid. ... It’s a particularly good example of his work. It picks up some of the same themes that you see at Coit Tower; and you see a downtown Richmond that doesn’t exist anymore.”

Though photographed and printed on vinyl, “It is very close to the original in both texture and color,” Cherny adds.

The mural was discovered by Melinda McCrary, executive director of the Richmond Museum of History. When she learned about the mural, in late 2014, she tracked down a janitor at the post office who found an upright triangular wooden crate marked “Victor Arnotoff October, 1976” in an unlit area of the basement at the post office.

McCrary went down there with a flashlight and two art handlers who crowbarred the crate to find a tube containing the rolled-up mural, with the art facing outward. It didn’t even have to be unrolled.

“I saw a face on the painting and was utterly astonished,” McCrary recalls. “I’ll be honest. I cried a little bit.”

It took another year, in which the mural survived a basement flood, to arrange a 25-year-loan from the U.S. Postal Service. The front of the painting is in good condition, but the back has been damaged by lead-based adhesive that was used to glue the canvas to the wall.

The mural has a notched bottom to fit over the postmaster’s door. McCrary already has a place on the museum wall picked out for it but it may take a while to get there because she needs to raise $50,000 to cover the restoration. She has a graduate degree in museum studies from San Francisco State, and knew that Cherny was at work on a book on Arnautoff. That’s what led to the mural’s debut in the campus library.

“It’s a great opportunity for them to showcase it and raise awareness,” McCrary says. “More people are going to see it and learn about it there than in Richmond.”

Arnautoff left San Francisco to return to Russia for good in 1963, and what he did not crate up and take home with him he left in the care of his son Vasily, a San Francisco longshoreman, who in turn left it with his own son Peter, a retired San Francisco firefighter who lives in Marin.

There has not been a solo show of Arnautoff’s work in San Francisco since the 1950s. Cherny was able to pick and choose from Peter Arnautoff’s collection for the exhibit, to cover the full breadth of the artist’s years in San Francisco, starting in 1925 when he enrolled in what is now the San Francisco Art Institute. He later had a 20-year career as an art professor at Stanford University.

Everything he did in between was political. The mural of Washington shows the first president off to the left, with his slaves front and center. Another panel shows him pointing west over the dead body of a Native American. Arnautoff drew political cartoons during the House Un-American Activities Committee hearings of the 1950s. One shows Sen. Joe McCarthy of Wisconsin, ringleader in pursuing anti-communist investigations, in a trash can. Another shows virulent anticommunist Richard Nixon carrying a bucket of red paint labeled “smear.”

Also included are images of mosaic murals that Arnautoff created in the Soviet Union, where he died in 1979.

Arnautoff’s murals were complex and filled with people and political subtlety. There were 27 muralists on the Coit Tower job, but Arnautoff was the muralist-in-charge and “City Life” set the tone. Looking at the reproduction, Cherny points out a scene lost in the background: It shows an automobile accident in front of the Pacific Stock Exchange.

“That, I think,” says Cherny, “makes it a stock market crash.”

Sam Whiting is a San Francisco Chronicle staff writer. Email: swhiting@sfchronicle.com Instagram: @sfchronicle_art

“Victor Arnautoff and the Politics of Art:” Opens Sept. 13, with a reception from 5-7 p.m. Viewable 1-5 p.m. Monday-Friday or by appointment. Through Dec. 12. J. Paul Leonard Library Special Collections Gallery, San Francisco State University, 1630 Holloway Ave., S.F. (415) 405-5571. www.sfsu.edu