Watermarked paper, preferably shadow-watermarked paper is produced in conventional manner and then size-press dyed using a pigment dyestuff composition. This results in unusual and attractive decorative effects as a result of preferential dye take-up in parts of the watermarked areas, resulting in enhanced contrast between watermarked and non-watermarked areas of the paper. The invention finds particular application in wallpaper base, but can also be used in decorative or security papers. The pigment dyestuff can be fluorescent for security paper use.