 Blackwell started out his career as an abstract-expressionist, but was moved to try his hand at the Pop art movement of the 1960s.It was with his Post-Pop paintings that Blackwell garnered early success; in 1969, his painting "Gook", which was a reaction to the horrors of the Vietnam War, was included in "Human Concern Personal Torment" at the Whitney Museum of American Art.As the artist recounted for the Currier Museum in 2015, "[i]n the late 1960s, I was still finding my voice as an artist.