New technique for monitoring ink-water balance on an offset press

Abstract

An acoustic technique, with microphone placed near the print nip exit on a sheet-fed offset press during trial printing of newsprint, was used to provide information relating to splitting of the ink-fountain solution film. The average acoustic power increased with tack of the ink used and with target optical density. Further, average power decreased during each run, reasonably strongly correlated to increase in fountain solution consumption. This indicates that average power is primarily sensitive to instantaneous tack of the ink-fountain solution film, and can be used to monitor tack and indirectly infer ink-water balance in the nip. Laboratory experiments were also performed using the Hydroscope instrument to simultaneously measure tack and average acoustic power of the splitting of inked rollers during fountain solution titration and evaporation. While these two measured parameters were not directly correlated over all conditions of emulsification, both decreased in tandem over intermediate amounts of fountain solution. Show more