Abstract: The electrostatic printing aid for gravure and flexographic printing machines can be operated with a voltage electrode whose dimensions have been reduced significantly, the print quality being kept at a high level. The voltage electrode, connected to a high voltage source, can be constructed with a bar-like or arc-like shape and to be non-contacting, or as a slip ring or as an electrically conductive brush. The voltage electrode is preferably arranged at one end of the three-layer impression roller of a gravure printing unit or the three-layer printing plate cylinder of a flexographic printing unit. The particular advantages of the arrangement reside in the significantly improved ease of servicing and the saving in costs, as early as at the time of purchase, in particular in the event of retrofitting printing machines already in operation.

Abstract: A process and an apparatus for electrostatic substance transfer are proposed. A substance (4, 4') is taken from a substance container (9) by a substance transfer roller (1) and transferred onto a printing form cylinder (2). In order to improve the substance transfer, the printing form cylinder (2) is subjected to local negative charging by means of a spray electrode (6) near to the region in which the substance transfer takes place. The substance (4) is subsequently transferred from the printing form cylinder (2) onto a medium (7) which is pressed against the printing form cylinder (2) by a back-pressure cylinder (3).