Rani Singh of the Getty Research Institute and Jack Brogan, conservator, inspect De Wain Valentine's Red Concave Circle in Brogan's studio in Inglewood, California, June 17, 2011. © De Wain Valentine

Llyn Foulkes stands by his work Flanders (1960–62) at the opening of his solo exhibition at the Pasadena Art Museum, September 18, 1962. Image courtesy of and © Llyn Foulkes

John Altoon smoking, ca. 1963. Image courtesy of Larry Bell. Photo by Dennis Hopper and © The Dennis Hopper Trust

Two Gray Walls, 1975–76, De Wain Valentine. Cast polyester resin. © De Wain Valentine. Photo courtesy of De Wain Valentine

Larry Bell’s studio in 1970. Photo by Larry Bell. Image courtesy of Billy Al Bengston

Slideshow: De Wain Valentine’s process of creating Gray Column, 1975–76. © De Wain Valentine. First, 4th, 5th, 6th, and 8th photo by and © Cathy Weiner; 2nd and 3rd photo by Sean Valentine

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

Betty Asher and Henry Hopkins in front of Ed Ruscha's painting The Los Angeles County Museum on Fire (1965–68), ca. late 1960s. © Ed Ruscha. The Getty Research Institute, Betty Asher Papers, Gift of Michael Asher, 2009.M.30

Vija Celmins in her studio in Venice, California, 1966. Photo by Tony Berlant. Art © Vija Celmins