Microscopic structure in Far Eastern paintings is largely unstudied. The properties and nature of the support (paper or silk) are important, and should be considered in conjunction with the paint layer. This point is the more significant since layered structures of the type seen in western paintings are largely absent. Some thicknesses of typical support materials are noted, as is the presence of secondary support structures (linings and repairs). Particle dimensions of pigments are briefly summarized. Paint layers are characteristically of an open structure on a microscopic scale, and particle dimensions in paintings are important both aesthetically and with regard to the interaction of paint layer and support. Such interaction involves consideration of the degree of sizing and other properties of the support, as well as pigment characteristics. The mechanical stability of the paint layer (resistance to flaking or detachment) is a complex question, depending on paint layer thickness, particle dimensions, proportion of medium, as well as support properties and mechanical strains that may develop. Author's address: Freer Gallery of Art, Washington, D.C. 20560, U.S.A.