A Realist painter and teacher born in Toledo, Ohio, Koch spent his childhood in Ann Arbor, Michigan. He first pursued his interest in painting at the art colony of Provincetown, Massachusetts, and then traveled to Paris, pursuing the study of art through long stretches of time at the Louvre. He admired the work of the Old Masters, and was particularly taken with Peter Paul Rubens. He joined the Internationale Union des Intellectuals, and though immersed in discussions of Surrealism, rejected the style’s influence on his own work.
Upon settling in New York City, he developed a bustling social life, developing close relationships with Edward Hopper, Paul Cadmus, Reginald Marsh, and Alice Neel, whose portrait he painted. Koch’s first solo exhibition was held in 1939 at the Kraushaar Galleries, where he continued to show his work in the ensuing years. His work received awards from the National Academy of Design in 1952, 1959, 1962, and 1964.
Partial to scenes of domestic intimacy, Koch frequently explored the relationship between models and the artist and conveyed a deep affection for objects through his still lifes. His personal art collection included paintings by John Singleton Copley, Jean-Auguste-Dominique Ingres, Peter Paul Rubens, and Édouard Vuillard.
Bumping up against the rise of abstraction, Koch became an advocate for placing representational art in museum shows