Control of Ink/Water Balance with the Help of an On-Line Densitometer

Controlling the water feed in the offset process is difficult because it is difficult to measure a thin water film with high accuracy. In this paper a method based on indirect measurement on the print with a densitometer is described. A method has been developed by GFL for controlling the ink-water balance. The method is based on a system consisting of an on-line densitometer connected to the water-feed system. A method has been developed by GFL for controlling the ink-water balance. The method is based on a system consisting of an on-line densitometer connected to the water-feed system. The principle of the method is that too low a water feed will lead to a sudden increase in half-tone print density, so that the detection of a tendency for the density in a half-tone area to increase may be used to keep the water feed above but close to the critical lower limit. The test runs have been carried out in a laboratory web offset printing press.