Abstract
Vinyl wallpapers were tested to clarify the discoloration mechanism. The samples were investigated by means of electromicroscopy, X-ray fluorescence and infrared spectroscopy. It was assumed that the cause of discoloration was the migrations of water and cobalt ions existing in putty from undercoat to wallpaper. Three methods of prevention of the discoloration were proposed: (1) application of wallpaper on dried undercoat, (2) avoidance of material which includes water-soluble colored components and (3) application of waterproof wallpaper.
