In the first part of this article, a mixing line for silica-based compounds was thoroughly described and its performance was studied in terms of mixing fingerprints. Along the mixing line, the compound experiences a large spectrum of strain, stress and temperature conditions such that important "cascade" or "stream" effects Occur. At a given point of the process, the material has an important strain-stress-temperature history that is obviously affecting its behavior during the subsequent steps, and the situation is further complicated by the in situ silanisation, which obviously must be complete for stabilized rheological properties to be obtained at the end of the line. In this second part of the article, results are reported which were obtained with a new and promising rheometrical technique, i.e., the so-called Fourier Transform rheometry, implemented on a commercial torsional dynamic rheometer. As shown, Fourier Transform (FT) rheometry provides a number of information about the complex set of events that occur along the silica-silane mixing line. Odd torque harmonics become significant as strain increases, and therefore the variation of torque harmonics with strain amplitude can be considered as the nonlinear viscoelastic "signature" of tested materials. Silica filled materials exhibit also a typical pattern, with a "bump" appearing in the 500% strain range, essentially on the third relative harmonic versus strain curves and changing as optimal silica dispersion and silinisation are achieved. The appropriate modeling of experimental results provide parameters with typical variations along the mixing line which are interpreted with respect to current views on the in situ silanisation process and are found in line with the mixing signatures analysis. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 112:1128-1141, 2009