A new KK (Morse-taper) sensor is suggested for rotational viscometry under slip effect. Theory of the sensor is presented, including the conversion of primary data into fluidity and slip viscometric material functions, as well as a statistical analysis of their relevance. The data treatment, based on the concept of local filtration, is illustrated on several aqueous solutions of Hercules CMC and Welan gum. (c) 2006 Elsevier B.V. All rights reserved.