Residence time distributions were measured for a Bliss Kneader, Kobelco Nex-T continous mixer as well as intermeshing co-rotating and counter-rotating twin screw extruders using polypropylene with aluminium flakes as a marker. Various modular screw configurations, screw speeds and feed rates were considered. Increasing feed rate and increasing screw speed the mean residence to shorter values and narrows the residence time distribution. Generally, in comparison of the different machines, the intermeshing counter-rotating twin screw extruder has the shortest mean residence time and narrowest distribution of residence times, while the Buss Kneader has the longest mean residence time and broadest residence time distribution.