De Wain Valentine and two of his studio assistants, Chris D'Arcangelo (left) and Keith Anderson (right), 1975–76. Photo © Cathy Weiner

Slideshow: Gray Column moves from conservator Jack Brogan’s studio to the J. Paul Getty Museum, 2011. Artwork © De Wain Valentine

Slideshow: Documentation of De Wain Valentine‘s Circle series of polyester resin circles, 1960s. Artwork © De Wain Valentine. Photo © Harry Drinkwater

De Wain Valentine in his Venice studio. Photo: © Cathy Weiner

De Wain Valentine in his Venice studio with one of his eight-foot Circle polyester pieces, 1970s. Artwork © De Wain Valentine. Photo © Harry Drinkwater

De Wain Valentine polishing Gray Column in 1976. © De Wain Valentine. Photo courtesy of De Wain Valentine

De Wain Valentine in front of Gray Column, 1975–76, during the polishing stage. © De Wain Valentine. Photo courtesy of De Wain Valentine

Ed Moses with his installation at Mizuno Gallery, 1970. Image courtesy of and © Billy Al Bengston

Mary Corse working in downtown Los Angeles in 1966. Image courtesy of and © Mary Corse

Mary Corse working in downtown Los Angeles in 1966. Courtesy of and © Mary Corse

Frederick Eversley polishing one of his sculptures, 1970. Image courtesy of and © Frederick Eversley

Frederick Eversley in his studio, 1971. Photo by Frank J. Thomas. Courtesy of the artist and the Frank J. Thomas Archives

An exhibition at Billy Al Bengston’s Artist Studio, with works by Ed Ruscha, Peter Alexander, and John McCracken, 1970. Image courtesy of Billy Al Bengston

John McCracken in his studio in Costa Mesa, California, in the mid-1960s. Photo by Frank J. Thomas. Courtesy of the Frank J. Thomas Archives

Robert Irwin, ca. 1967. Photo by Frank J. Thomas. Courtesy of the Frank J. Thomas Archives