Ultrasonic Systems for Liquid Absorption Measurement: Ultrasonic Systems for Liquid Absorption Measurement, 2005 Papermakers Conference

Back trap mottle (BTM) has been a long term problem that influence the quality of multi-color printed material. Recent work has demonstrated that non-uniform ink setting is the basic cause of the problem, but a quick test for the potential for BTM has not been reported. The objective of this work is to determine a rapid test for quality control of coated and uncoated papers or boards. The work reported here includes tests that measure the absorption rate and its uniformity of fountain solution. Eight samples that have been used in previous studies are characterized with the absorption test and with image analysis. The results are compared to the degree of back trap mottle. Variation of absorption of fountain solution in one mm scale measured on Penetration Evenness Analyzer showed good correlation with print mottle if a proper “cut time” of liquid penetration was selected. Application: This study shows that Penetration Evenness Analyzer (PEA) should be able to serve as rapid test for quality control for determination of liquid absorption uniformity and prediction of paper contribution to printability. Rapid testing on PEA will reduce the testing time which will help to maintain stable product quality, reduce the amount of broke during the grade change and accelerate the troubleshooting and new grade development.