A New Graphical Format which Illustrates the Different Ways in which Ink, Water, Paper, Plates, and Blankets can Affect the Tone Reproduction Characteristics of a Given Printing Press Unit

In the work reported on in this paper, each printing unit on a press is treated as a stand-alone reproduction process in which the film from which its plate is made is considered as the original, and the corresponding print the reproduction. Within this context, a new format for a print characteristic curve is defined which displays all three of the print properties which govern the tone reproduction characteristics of a press unit; the density of the printed ink film, the size of the printed dots relative to the original, and the picture contrast. Picture contrast, not to be confused with print contrast, describes the rate of change of the density of the reproduction with respect to the density of the original, and is analogous to the property gamma used in photography. Sample data from single color printing tests on a sheetfed press are plotted to illustrate the diverse ways in which tone reproduction characteristics of the test unit were affected by changes in ink feedrate, water feedrate, ink tact, fountain solution composition, paper grade, type of blanket, blanket packing, and type of plate.