Determination of the Fountain Solution Picked Up by the Paper and Ink in Offset Printing, 1996 International Printing & Graphic Arts Conference Proceedings

Peter Y. W. Lim

Union Camp Corporation

Chester J. Daniels and Robert E. Sandholzer

Rochester Institute of Technology

Fountain solution plays a key role in offset printing but is difficult to measure quantitatively in terms of the amount picked up by paper. Even more difficult is differentiation between printed and unprinted area. The difficulty arises from two major sources. First, the amount of the fountain solution picked up is a very small quantity below the detection limit by gravimetric methods. Second, the fountain solution is applied by multiple roller train systems and evaporation takes place before the solution reaches the plate and the paper. An analytical approach was developed, and the amount of the fountain solution picked up by the paper and the amount in the image areas are accurately determined. Consumption of fountain solution was simultaneously monitored and compared with the results obtained by the analytical method. Net difference was taken as the amount of the fountain solution lost in transit and evaporation, and a material balance was established. The fountain solution picked up by the ink in the image area was much higher than that of the unprinted area of the paper. Quantitative understanding thus obtained as to what happens to the fountain solution provides critical information required for understanding the printing process mechanism in offset lithography. This also provides insight for understanding the difficulties involved in a combined printing operation of conventional and electronic printing such as in preprinting with offset followed by laser printing. The experiment was done at RIT with Komori Lithrone 26, 26” two-color sheet fed offset printer.