Gilbertson is best known for his contributions to Raku pottery. Before 1960, few Americans were making Japanese-style raku. Gilbertson, who had studied raku in Japan, was one of the first to call attention to the making of Japanese raku tea bowls, pioneering the modern American raku ceramics movement. His ceramics are simple in form and subtle in color, like this typical bowl shape with several splashes of colored glaze and three fish etchings. However, his works’ simplicity is deceptive, hiding all of the time and technical skill he spent mastering Raku.