engleski

Analysing of the Surface Roughness oOf non Printng Elements on CtP Thermal Offset Plates

A printing and non-printing surface structure of the offset printing forms are key factors in maintaining the conventional offset printing. The most significant characteristics of these surfaces are: physical and chemical properties, surface tension and roughness. During the printing process these characteristics change and directly influence the print. Both the processing of the printing plate and the development of the printing form can affect above mentioned surface characteristics. In this paper, the behaviour of the non-printing surfaces of the thermal CtP plates, developed in fresh developer and used for a print run of 300.000 copies on a web offset heat-set printing press is investigated. The changes of the non-printing areas and their roughness are observed before, during and after printing by a roughness meter (TR200, Time Group) and by a Scanning Electrone Microscope (SEM). The investigations reveal the appearance of the physical and chemical changes as well as the geometrical ones.

Non-printing elements; surface roughness; thermal CtP plates; print run

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