This method is used to provide a quick, reliable means to measure the average wet zero-span tensile strength of a random, standard aggregate of pulp fibers. The standard aggregate is produced by making a handsheet (see TAPPI T 205 Forming Handsheets for Physical Tests of Pulp) from any papermaking pulp.
The test requires an apparatus comprised of two adjacent, precisely aligned clamping jaws in initial intimate contact (zero-span), which can be made to reliably and reproducibility exert a very high, optimum and uniform clamping pressure on fibers in a specified test specimen after they have been wetted using a defined procedure. While firmly clamping the wetted fibers, the clamps must be able to separate at a defined uniform rate of loading until the sample fails. The failure point under the test conditions is called the wet zero-span tensile strength.
The test is most commonly used to assess the retention of average individual fiber strength of the pulp through chemical processing in pulping and bleaching.
