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.
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This page is maintained by Martin hubbe, Associate Professor of Wood and Paper Science, NC State University, firstname.lastname@example.org .