Factors influencing paper friction and its reproducibility: is third test best?

This paper explores the suitability of the TAPPI standard (T816 om-92) for determining coefficient of friction of paper materials. Three assumptions of the TAPPI method are tested. Namely: More than one slide improves test to test variability. Third slide result represents given applications better than the first slide result. Different surface to surface materials can be treated in the same way. i.e., give the same relative results albeit of different magnitudes but retaining relative sample ranking. Tests on three different paper products suggest that test result variability is not improved after the second slide. The first slide result of a friction determination corresponds to the third slide result and different test surfaces impose different test conditions and cannot be directly compared. Testing time can be cut by two-thirds by only reporting the first slide result. The observation that the contact time before starting a slide increases the static coefficient is explained with a simple qualitative model.