Abstract: A dummy plate is provided for offset printing which essentially consists of a plate-, sheet- or band-form, mechanically and/or electro-chemically roughened, anodically oxidized and optionally hydrophilized aluminium support and a non-photosensitive, water-soluble protective layer applied thereto, characterized in that the layer contains a water-soluble organic compound which contains at least one OH- or NH-acidic group having a pKa value of ≦8 as acid or salt, and has a layer thickness which is smaller than the average roughness ra of the support material, determined by optical means. Even after extended storage at elevated temperature, the dummy plate can easily be used without an additional development step and exhibits no tendency to stick.

Abstract: A dummy plate is provided for offset printing which essentially consists of a plate-, sheet- or band-form, mechanically and/or electro-chemically roughened, anodically oxidized and optionally hydrophilized aluminium support and a non-photosensitive, water-soluble protective layer applied thereto, characterized in that the layer contains a water-soluble organic compound which contains at least one OH- or NH-acidic group having a pKa value of .ltoreq.8 as acid or salt, and has a layer thickness which is smaller than the average roughness ra of the support material, determined by optical means. Even after extended storage at elevated temperature, the dummy plate can easily be used without an additional development step and exhibits no tendency to stick.