A Method for Measuring Tack Build of Offset Printing Inks on Coated Paper

A test method for studying tack behavior of offset printing ink on coated paper is described. Originating as a strain gage connected to a strip chart recorder, S. D. Warren's Lodcel test has evolved into a modern test system. Essential elements of the current test include a load cell force transducer, paper holding mechanism, analog-to-digital converter, Vandercook proof press, and a microprocessor. The computer collects, processes, and stores all data, generates hard copy graphs of results, monitors press conditions, and enforces adherence to standard operating procedure. Options are provided for force re calibration, barcode identification, on-screen timing, and in-depth analysis of force measurements. Standard papers are used to keep Lodcel test results in statistical control. The Load cell test has proven useful in interpreting such diverse printing phenomena as carryover piling, backtrap mottle, wet trapping, and set-off.