Dummy plates

The invention discloses a blank plate used for offset printing. Mechanical or electrochemistry (anodic oxidation) is used for generating roughened grains. A surface oxide film is firm and has the advantages of wear resistance, good hydrophilicity and light weight. A protective layer which comprises non-photosensitive water soluble organic compound is arranged on an aluminum matrix supporting body with high wear resistance. Under the condition that the environmental temperature is improved, the effect of repulsing ink is guaranteed completely during printing. Under the environment with high humidity, the protective layer on the surface is not provided with trends of stiffening and mildewing. A homemade edge grinding machine is used for ensuring that no burrs and turned edges along WE direction (the rolling and pressing direction of aluminum) appear in every pack of plates. And the working requirement of the automatic printing machine can be satisfied. The thickness of the water-soluble protective layer after b