Principles of Developing a Softness Evaluation Technology for Hygiene Paper

In developing objective tissue softness evaluation methods, reliable and reproducible subjective evaluation data are a prerequisite. A trade-off relationship generally exists between the relevance to a consumer’s in-use situations and the test variability. At present, sensory panel test (SPT) has been most widely used. It provides the least variable data, but it has the problem of being the least relevant to the real world. Recently we have developed a new sensory panel test which is referred to as new sensory panel test (NSPT). It performs like a HUT (home-user-test) for the relevance and like a physical test for the test variability. Since the pioneering work by Hollmark, it is now widely accepted that subjective tissue softness should primarily consist of the bulk softness component and the surface softness component. The bulk softness component can be determined by the tissue flexibility. The surface softness component can be determined by measuring the surface roughness and the surface friction. In the present study, the NSPT was performed on 7 commercial bathroom tissue products. For subjective softness evaluation, the Thurstone interval scale values have been determined for the 7 products. For the bulk softness component, the flexibilities of these samples were measured using a tensile tester (Criterion model-41, MTS, U.S.A.). For the surface softness component, the surface roughness and the surface friction were measured using the surface roughness/ friction tester (KES-SESRU, Kato Tech., Japan). The result validates the hypothesis that the bulk flexibility and the surface roughness/friction should be sufficient for developing an objective tissue softness evaluation method. KCI Citation Count: 0