Buckling and flat cleavage are defects characteristic of paint on wood support because wood is the only common support material that puts paint under large compressive forces. Includes discussion of the me-chanical properties of wood and how they vary with moisture content; specifically, the phenomenon of warping. Treatment by use of a supplementary panel taking these mechanical properties into consideration is described. The author uses balsa wood cut across the grain as the bulk material of this panel. See also 15-1131 and 1498.