water and silicone oil is still higher, indicating a weaker effect. Onlyin presence of SiO2 a significant smaller value can be detected.However, in this case no Janus droplets are formed.The results obtained from spinning drop experiments are listedin Table 5. It can provide a good agreement with the results obtainedby the ring method.The results bring forward two central factors that merit an anal-ysis. At first the effect of viscosity of the silicon oil was unexpectedlylarge with the primary effect being larger drops for the oil withgreater viscosity, but with the contact angles similar. This resultaccentuates the fact that the formation of emulsions [21] is a kineticprocess and that drop division in the emulsification process [22]strongly depends on the viscosity of the dispersed phase. This corre-lation appears restricted to emulsions with combined surfactants.When only the water soluble Tween 80 is applied, Fig. 1 (emul-sions 1 and 2), an approximately equal contact angle is found, butthe low viscosity silicon oil forms substantially smaller drops, asmentioned. However, for the emulsions with mixed surfactants thecontact angle varies strongly, ≈90 ± 60◦, when different orientationis taken into account, Fig. 1 (emulsions 3–6). Similar variations areobserved for emulsions stabilized by phospholipid surfactants, asto be seen in Fig. 2.Evidently, kinetic factors play a more significant role for systemswith the latter surfactants, indicating the phospholipids as surfac-tants requiring longer times to reach a lower energy state than thesingle water soluble variety. Obviously, more research is neededto confirm this hypothesis, but in lieu of additional information,it is useful to point toward the fact that phospholipids form liq-uid crystals and, subsequent, vesicles during high energy treatment[23]. These processes in a water/oil system will also include trans-port over the interface with temporary interface structural changes,which latter may be affected by the interface per se and long termmodification of the system is certainly expected [24]. More com-prehensive investigation of the emulsification process is evidentlyneeded.Additional support for the view that kinetics plays a more sub-stantial role is the fact equilibrium calculations of the olive/siliconoil interfacial tension from the measured interfacial tensions,Tables 4 and 5, do not result in realistic values. Evidently, thisdiscrepancy is not due to measurement inaccuracy; the agree-ment between the results from two different methods is excellent.Instead the possibility may be considered that slow transfer ofsurfactant between the three phases causes pronounced modifi-cations of interfacial structure. Admittedly, such measurementswould be time consuming in systems, in which all three liquidsplus added surfactant are equilibrated, prior to measurement. Acombination of such measurements with structural studies in moreconcentrated systems may provide answers in an emerging difficultarea of emulsion science.