The effect of offset printing plate deformation on print quality

Abstract

To be able to make quality prints on uncoated paper, it directly depends on the printing system, the physical properties of the substrate, the ink and ink drying method, the plate properties and the number of prints, the printing room conditions, and the properties of other main and auxiliary materials used in printing. Web offset printing system (heat-set), uncoated paper, CtP plate preparation, heat-set inks, and drying methods were considered in this paper. For prints made on uncoated papers, the loss of quality caused by the wear of the printing plate due to physical and chemical effects during the printing process was examined practically by test printings. For this purpose, 180 000 test prints were made with thermal CtP
plates used in heat-set printing. Microscopic and three-dimensional/topographic images of the surface were taken before and after printing, and their areas at the level of micrometer square (µm2) were measured. Dot size deformation was also visually examined and evaluated, depending on the number. For high volume print run on uncoated paper, it was determined that the plate must be replaced per 150 000 impressions or baked before printing.