Mini-Encyclopedia of Papermaking Wet-End Chemistry
Part Two: Definitions and Concepts

Plane of Shear

The plane of shear is a hypothetical location about 2 nm from the surface of a particle suspended in a typical sample of papermaking process water. Most phenomena related to surface charge and zeta potential can be explained by a model in which counter-ions closer to the particle that the plane of shear act as if they are attached to the particle. By contrast, ions outside of the plane of shear act as if they are part of the surrounding solution. The zeta potential is defined as the electrical potential at the plane of shear. Despite the fact that the location of the plane of shear usually is unknown, zeta potential values have been very useful for predicting whether suspensions are likely to coagulate.

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This page is maintained by Martin hubbe, Associate Professor of Wood and Paper Science, NC State University, .