While young he was one of a relatively small number of American painters whose work was termed modernist and, as he matured, he grew to be one of the best known among them. By the early 1930s critics had begun to take note of Knaths and give his work more than a passing mention. In 1931 the critic for the New York Sun could say that his work had been known in the art world for quite a few years and was fairly widely collected. While abstract, his paintings possessed, this critic wrote, "a very individual kind of realism." "One feels in his work," he went on, "a love for the medium, rich textural quality, and a very unusual color harmony which varies with the subject." By the late 1940s appreciative notices such as this one became reasonably common. Beginning about 1944 newspaper art critics more frequently would analyze and usually praise his work rather than simply listing it as appearing in a show. For example, in that year A. Z. Kruse wrote a piece about his work in the Brooklyn Daily Eagle and in the late 1940s his work was featured in articles in Art News and the New York Times. In 1949 he was featured in an article by Elaine de Kooning, "Knaths Paints a Picture," in Art News.
