New dusting propensity analyser

Dusting is a common problem in papermaking, printing and paper converting. Specifically in offset printing, linting has become a growing problem, when lower cost materials and higher printing speeds are being used. Today, papermakers try to use more filler pigments because the filler price can be only 20-40 % of the fibre price. Unfortunately, fillers are not bound to fibres and they also prevent bonding between fibres, resulting in reduced strength, dusting and linting. Most paper machines produce a two-sided filler distribution and two-sided fibre bonding. The side with less bonding normally has a higher dusting propensity, the same applies for the side with higher filler content. The wire section has the greatest effect on filler two-sidedness and the press section on bonding two-sidedness. It is clear that there can be quite rapidly-changing variations in filler content and its two-sidedness, as well as in fibre bonding and its two-sidedness. Particularly when using recycled fibres, there are wide variations and they can be rapid. Also, changes in the broke proportion and recycled stock from the saveall have an effect on dusting propensity. Traditionally, dusting propensity has been measured in the laboratory. The delay time from process change to the result of laboratory measurement is at least one hour, normally much more. In addition, the laboratory sample represents a very small part of the total paper production, while, for example. true linting in offset printing tests 100 % of the paper surface. Consequently, the laboratory testing is not a satisfactory measurement. Linting is a cumulative process and very short high linting periods can cause severe problems in printing. ACA Systems Oy has developed a new Dusting Propensity Analyser (DPA), which is used online on a paper machine. Results are available after some minutes, depending on the severity of the problem.