Abstract: The mechanical roughening of the surface of a printing plate substrate comprising aluminum or an aluminum alloy is carried out by wet brushing with the use of a cylinder brush 1 in which brush rows 2, 3 having bundles of organic fibers 22 and metal wires 33 are arranged side by side on the surface 7. The suspension used for the wet brushing contains from 5 to 80% by weight of abrasive particles in water.

Abstract: The mechanical roughening of the surface of a printing plate substrate comprising aluminum or an aluminum alloy is carried out by wet brushing with the use of a cylinder brush 1 in which brush rows 2, 3 having bundles of organic fibers 22 and metal wires 33 are arranged side by side on the surface 7. The suspension used for the wet brushing contains from 5 to 80% by weight of abrasive particles in water.

Abstract: With an infrared radiator, the surface temperature of which is kept constant during measurement, a measuring area on a roughened material surface is thermally irradiated with oblique incidence of the rays. The temperature of the reflected thermal radiation is measured by an infrared thermometer, which is arranged above the measuring area in such a way that the reflected radiation falls into the area of coverage of the infrared thermometer. The entire measuring area of the material surface which lies in the field of coverage of the infrared thermometer must be thermally irradiated. The measured temperature variation of the reflected radiation in dependence on the known surface roughness of the material is stored in a comparison device. This comparison device is fed a set value for the desired surface roughness.