Analysing the relationship between ink coverage and variations in sheet grammage and topography

摘要

The print quality of an offset printed newsprint sheet depends on a range of paper properties, however, these properties do not necessarily make an equal contribution to print performance. Newsprint sheets made from Pinus radiata are generally considered to be rougher than sheets made from many other furnishes due to the relatively high mean coarseness of radiata fibres. The purpose of this study was to determine the degree to which the roughness of the sheets made from radiata fibres influenced the ink coverage and to also determine the relative influences of grammage and topography.rnThe influence of surface topography and grammage on ink coverage was investigated for the same printed localities (approximately 20 mm × 20 mm). Analysis was performed in two ways: A) correlation analysis of square areas of inspection, of a range of sizes; B) analysis of regions that had remained uncovered by ink.rnGrammage variability had a greater influence on ink coverage than did topography variability. Uncovered regions in the sheet surface tended to be of either low relative grammage or topography. However, where unprinted regions occured in zones of high relative grammage they tended to be located in local topography troughs.