Günther Uecker is best known for his undulating reliefs using hammered nails, the signature medium he began to explore in the late 1950s. Active while Piero Manzoni and Lucio Fontana were similarly turning to nontraditional materials and techniques, Uecker joined the avant-garde Group Zero in 1961 with Heinz Mack and Otto Piene. Influenced by studies of light, optics, oscillation, and electricity, Uecker has created series of “light nails” and light boxes, kinetic nails (including revolving sacks of nails), and kinetic installations and machines using sand and water. He also used nails to scratch motifs into wet paint and to turn furniture and objects into bristling sculptures.