Ever greater attention in the rubber industry is being applied to effectively measuring the degree of silica dispersion that has resulted from established factory mixing procedures. This process is particularly complicated because of the rubber phobic nature of silica (compared to carbon black), the required use of an organosilane and required mixing temperatures to be effective, and the need to establish differing degrees of total work history during the mixing process. Three years ago a new standard method for measuring the Payne Effect was developed as ASTM D8059 using the RPA. Also, in 2011 a standard method was developed using a reflected light microscope to measure state of mix under ASTM D7723. In this study, a Premier® RPA Rubber Process Analyzer was used to measure the differences in rheological behavior by using SBR and TESPT with variation in the applied work history during mixing. Processability characteristics as seen in the Payne Effect were measured for these mixed stocks with varying work histories using the RPA with Extended Dynamic Range Technology. Comparisons were also made with the AlphaView DisperGrader, reflected light microscope under special conditions.