(EN) The product is characterized in that it is comprised of a base sheet which may have a composition of paper fiber or a synthetic composition and which is covered or coated with a layer consisting of dyes of the type lactones or spiropyrannes or metal iron complexes which react with weak organic acids, and the layer also including an inorganic phosphorescent pigment of the type ZnS:Cu having a particule size which is appropriate to produce phosphorescence within predetermined time and wavelength thereby confering to the sheet combined properties of printability and phosphorence.