Mini-Encyclopedia of Papermaking Wet-End
Part Two: Definitions and Concepts
Before the paper is ever dried, it already has some strength. The strength of a partly-dewatered or wet-pressed sheet is called "wet-web strength" or "green strength." This characteristic has nothing to do with wet strength. Rather, wet-web strength is dependent on such factors as fiber length, the coefficient of friction between adjacent moist fibers, and capillary forces in the liquid meniscus between two fibers. Wet-web strength can be increased by increasing the relative amount of softwood fibers, by more effective wet-pressing, and by decreasing the level of surface-active agents in the furnish. Paper with high wet-web tensile strength at a given solids level tends to run faster and with fewer web breaks on paper machines that have open draws before or within the wet-press section. Sometimes the best predictor of runnability is the relationship between wet-web tensile strength and the percent stretch to breakage.
Request from the webmaster: Our goals include brevity and accuracy. Hopefully we have succeeded with the first goal without sacrificing the second. Please let us know right away if you find an error or omition. Also, please indicate points that need a clearer description.
RETURN TO INDEX PAGE OF ENCYCLOPEDIA
This page is maintained by Martin hubbe, Associate Professor of Wood and Paper Science, NC State University, email@example.com .