Arnold started as a watercolorist but became an admired printmaker. His work appeared in more than 225 exhibitions, including solo shows at the Cleveland Institute of Art, Oberlin's Allen Memorial Art Museum and elsewhere. Fifteen museums have collected his work, including the Allen, Cleveland Museum of Art and Library of Congress. He grew up mostly in China, where his father worked for the YMCA. He said his earliest memory was of camel caravans. Arnold earned bachelor's and master's degrees in art at Oberlin and met his future wife, schoolmate Sarah Ann Clagett. He later earned a master's of fine art at the University of Minnesota. He taught in Oberlin in 1941, joined the Army the next year and spent 1944 to 1946 in China with the Office of Strategic Services. He became a captain and earned a Bronze Star. Back at Oberlin, Arnold was asked to teach printmaking and became a leader in the field. He studied woodblock technique in Japan with the famed Toshi Yoshida. He tried to combine shapes and colors in what he called a "lively, yet disciplined, unity." The professor had three stints chairing the art department. Pearson praised his "patience, diplomacy, fairness and generosity" in the role. Arnold also directed the college's Peace Corps Training Program and East Asian Language and Area Center. He was president of the College Art Association and the National Association of Schools of Art and Design. He spent terms as a visiting professor in Taiwan and in Lacoste, France. He led Oberlin alumni on tours of France and five Asian countries.