Felt marks, wire marks, Periodic patterns in the sheet: how they affect print quality

摘要

For printing grades, periodic patterns within the sheet such as felt marks and wire marks can appear in the print, decreasing product quality. For uncoated fine paper a new technique for detecting and quantifying these patterns has been applied to formation images of unprinted sheets and to scanner images of offset print areas (100 % black, Heidelberg press). In some cases.the periodic patterns observed in the formation of the sheet were transferred in the print; in other cases, not. Differences in surface properties of the sheet (topography...) probably explain this variety of observations.