A series of physical softness models were developed for facial tissue products. To this end, subjective softness data were obtained by panelists by means of round-robin pair-comparison methods. Overall softness was found to mainly consist of bulk and surface softness. Bulk softness was determined by measuring the tensile modulus (TM) from tensile testing. In contrast, the surface softness considered the mean absolute deviation (RMAD) from the roughness average (Ra) and the mean absolute deviation (FMAD) from the average coefficient of friction ( ), respectively, which were determined by profilometry. The developed models exhibited strong correlations with subjective softness. In particular, surface softness was found to contribute more to the overall softness than bulk softness. Overall, the developed models can serve as guidance for developing tissue products.
