The discoloration of pigments during exhibition, which includes the blackening of lead white or red lead and the reddening of azurite or malachite (copper-containing pigments), is caused by formaldehyde and other organic compounds emitted by the plywood and adhesives used in the construction of display cases. The fact that display cases may heve adverse effects on art works has been a growing concern in recent years. Presented here as a case study is the damage caused to lead-containing pigments on a Japanese screen during temporary echibition. The interactio between pigments and the diaplay case environment is discussed.