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

Judson Powell, Noah Purifoy, and Sandra Corrie in the exhibition 66 Signs of Neon, University of California, Los Angeles, 1966. Photo by Harry Drinkwater. Image courtesy of and © Harry Drinkwater