Abstract: A process for roughening aluminum or aluminum alloys useful as support material for printing plates, in which process two electrochemical roughening steps are carried out in direct succession and are followed by a pickling step. Printing plates are produced from this support material by coating with light-sensitive coatings, which printing plates, when exposed and developed, give corresponding printing formes of very uniform topography, high run stability and good damping agent supply.

Abstract: A method for changing a metal body, especially an aluminum alloy body, and, in particular, a method for producing a uniform metal body surface for use in achieving desired light reflectance characteristics and/or other useful attributes. The method comprises (a) preparing a metal body in a first solution by producing a first coating on at least a desired portion thereof with the first coating providing a substantially continuous outer surface on the metal body and (b) treating the metal body to achieve substantial uniformity throughout the desired portion of the metal body. In the treating step, substantially all of the first coating is removed in a second solution. The metal body has a substantially uniform roughened surface after the treating step which is sufficient to substantially optimize diffusive reflectance and reduce spectral reflectance of the metal body surface. The preparing step is preferably accomplished by anodizing.

Abstract: A method of electrolytically graining aluminium, aluminium alloy or aluminium laminate, desirably in a substantially uniform manner, in particular for use as a lithographic printing plate substrate, is disclosed wherein the graining is effected using a square wave alternating current.

Abstract: A process for direct zinc electroplating of aluminum strip which can be performed continuously at a high speed and a high current density. The process comprises pretreating aluminum strip by alkaline degreasing and then pickling and subjecting the pretreated aluminum strip to zinc electroplating in an acidic zinc plating bath which contains, in addition to Zn.sup.2+ ions, metal ions selected from the group consisting of Ni.sup.2+ ions and Fe.sup.2+ ions in a concentration of at least about 10 g/1 to form a Zn-Ni, Zn-Fe, or Zn-Ni-Fe alloy plated coating, which may be overlaid with another zinc electroplated coating.

Abstract: Aluminum, or an alloy thereof, is grained in a two-stage process wherein it is subjected to an electric current while immersed in an acidic electrolyte solution, such as a solution comprised of hydrochloric acid and aluminum chloride. Current density in the first stage of the process is at least as great and preferably substantially greater than in the second stage, while both treatment and time and current consumption in the first stage are less than in the second stage. The process provides a fine uniform grain that is essentially free of pits and is especially beneficial for use in the manufacture of aluminum supports for lithographic printing plates.

Abstract: An improved method of making a lithoplate from a 5XXX type alloy which includes controlling the composition and casting practices to eliminate forming a pine tree metal structure in an ingot used for rolling a workpiece to be made into lithoplate. The method also includes homogenizing and hot rolling the ingot at a controlled initial temperature to produce a desired grain and metal microstructure in the sheet rolled from the ingot which is suited for providing a surface having substantially uniform and evenly distributed craters produced by an electrochemical method of graining.

Abstract: Improved lithographic printing plates comprise an aluminum support which has been grained in a novel two-stage electrolytic graining process and a radiation-sensitive layer capable of forming a lithographic printing surface. The aluminum support is subjected to an electric current while immersed in an acidic electrolyte solution, such as a solution comprised of hydrochloric acid and aluminum chloride. Current density in the first stage of the process is at least as great and preferably substantially greater than in the second stage, while both treatment time and current consumption in the first stage are less than in the second stage. The process provides a fine uniform grain that is essentially free of pits. Any radiation-sensitive layer is suitable, which after exposure and any necessary developing and/or fixing provides an area in imagewise distribution which can be used for printing.

Abstract: An aluminum alloy substrate for presensitized plates for use in making lithographic printing plates comprises an aluminum alloy plate composed of not less than 0.05% by weight and less than 0.5% by weight of Si; 0.2 to 0.7% by weight of Fe; 0.3 to 1.5% by weight of Mn; less than 0.5% by weight of Cu; and the balance of aluminum and unavoidable impurities, the surface of the aluminum alloy plate being subjected to electrolytic graining treatment. The aluminum alloy substrates for PS plates are favorable for appropriate electrolytic graining treatment and show good printing properties and sufficient strength suitable for high-speed printing operation.

Abstract: A mechanically roughened substrate is conveyed through an electrolytic bath and is given a superposed electrochemical roughening, which is carried out by means of electrodes which are arranged in the electrolytic bath at a specific spacing from the substrate. The electrodes are connected to corresponding windings on the secondary side of a three-phase transformer. The corresponding windings on the primary side of the three-phase transformer are connected to a three-phase frequency converter, to which three-phase current is applied via leads. The three-phase frequency converter transforms the line frequency of the three-phase current supplied into a frequency range of about 50 to 300 Hz at a voltage of between about 1 and 380 V.

Abstract: A process for producing an aluminum support for a lithographic printing plate is disclosed, which comprises etching a surface of an aluminum plate, particularly an aluminum plate containing manganese, with an alkali etching solution in such a manner that from 0.01 to 1.0 g/m.sup.2 of aluminum is removed, chemically etching in an aqueous solution containing sulfuric acid in such a manner that from 0.001 to 5.0 g/m.sup.2 of aluminum is removed, and subsequently subjecting the aluminum plate to electrolytic graining in an acidic electrolytic solution. The aluminum support has a uniform grain and provides a lithographic printing plate excellent in printing durability and stain resistance.