Abstract: A support for a lithographic plate and process for producing a support for such a plate are described, which process comprises:mechanically roughening the surface of an aluminum plate,chemically etching about 5 to 20 g/m.sup.2 of aluminum from the surface of the plate, andapplying an alternating wave-form electric current to the plate in an acidic aqueous solution such that the quantity of electricity generated with the plate as the anode is equal to or greater than the quantity of electricity generated with the plate as the cathode, electrolysis being carried out such that the current density when the plate is the anode is not less than about 20 A/dm.sup.2 and the quantity of electricity generated with the plate as the anode is about 200 coulombs/dm.sup.2 or less.

Abstract: A method of stacking metal sheet materials which is characterized by interposing between each adjacent metal sheet material an interleaf comprising paper with plastic coated on only one side.

Abstract: A method for preparing a support for a planographic printing plate using an electrolytic surface treatment of an aluminum plate is disclosed, wherein an alternating charge voltage is applied to the aluminum plate in an acidic electrolyzing bath, and the wave form representing the voltage includes an intermission of zero voltage in at least one of the anode or the cathode phases, and is such that the electric quantity for the anode phase is larger than the electric quantity for the cathode phase.

Abstract: A method for electrolytically graining the surface of an aluminum plate which comprises passing an alternating current through the aluminum plate in an acidic electrolyte so thatQ.sub.1 >Q.sub.2 <Q.sub.3wherein Q.sub.1, Q.sub.2 and Q.sub.3 represent the quantities of electricity per unit area of application, respectively, during the first 1/3 period, the intermediate 1/3 period and the final 1/3 period of the total electrolytic graining time.