The Character and Magnitude of Color Variations on Press

Two different types of color variations on lithographic presses are identified, and means for quantifying them are described. The magnitudes of such variations, in terms of density and delta E, are determined as a function of tonal area and the number of overprinted colors for three typical presses: a 28 inch sheetfed press and a 40 inch sheetfed press without closed loop color control, and a 38 inch web press with closed loop color control. A strategy for reducing color variations on a given press is outlined, based on this work.