sentences:  More specifically, between 1952 and 1958, Hedrick begins his kinetic junk assemblages, beer can sculptures and 'Black Painting' series.Not only do Hedrick's junk kinetic beer can sculptures, now all lost or destroyed, possibly rank as the seminal "kinetic junk sculptures...made before Tinguely", but also, Hedrick is one of the first American artists to oppose US intervention in South Vietnam.Some artists at the time considered Hedrick a 'pre-conceptualist'