contrast when annealed foil rather than hard foil was used the graining response was not as uniform and larger plateaus were encountered with rougher pitting when the electrograining treatment time was reduced from 30 seconds to 20 seconds it was found that the surface produced on the bright rolled side had more plateau areas and the rolling direction could be readily discerned by the unaided eye while the matt side was satisfactory fig3 and 4 are photomicrographs of these two surfaces thus a light electrograining treatment on the matt pack rolled side of the sheet produced a litho sheet support that looked as though it would have had useful properties ribbons of aa1050a aluminium sheet 0 65 mm thick in an annealed condition achieved by a recovery anneal at 400 u00b0 c for 5 minutes were pack rolled to give rise to sheets approximately 0 425 to 0 485 mm thick the front matt surface of some of the samples was electrograined at 70 amps for 5 seconds in 1 5 hydrochloric acid this treatment results in a charge input about 25 of that required for commercial electrograining of conventional rolled sheet the various samples were anodised to generate an anodic oxide film on the roughened surface at a rate of 2 4 g m 2 profilometry measurements were made using a mechanical stylus it is accepted that a mechanical stylus gives roughness figures about half those obtained using a non contact profilometer commercial litho sheet support has an r a roughness typically in.