This paper describes the materials and techniques used by Sloan during two distinct periods of his painting career: his use of Hardesty Maratta's color system and the Maratta Colors from 1909-1927, and the changes in his materials and methods of painting after this time. Later works are painted in an indirect manner in contrast to his earlier direct, opaque application of oil paint. In addition, Sloan made changes in his painting medium, supports, and subject matter. An appendix includes information on the condition and treatment of several paintings. -- AATA