Surface Characteristics of Ball Grained and Brush Grained Aluminum Lithographic Plates.

Many types and degrees of graining are offered in the lithographic industry, and a need exists for techniques that can define and describe the surface roughness obtained. Scanning electron micrographs, gloss and reflectivity measurements, surface composition analysis, and gas adsorption measurements were utilized in this work, and their application was demonstrated on typical ball and brush grained aluminum surfaces. The effect of graining on the surface appearance after anodizing was also studied. Comparative data generated by these various techniques served to illustrate how ball and brush grains differ. This in turn provides a basis for defining and evaluating any type of lithographic graining, as another aid in producing effective plates.