There is disclosed herein a method of measuring and profiling a process liquid in a process vessel. The process liquid includes an emulsion layer between two media of differing dielectric constants. An electromagnetic signal is generated and transmitted along a probe, defining a transmission line, extending into the vessel. The transmission line comprises a conductor in contact with the process liquid with an insulating coating on the conductor to maximize signal penetration in the process liquid. A reflected signal is received from the transmission line and a programmed controller is operatively connected to the probe for measuring characteristics of reflected signal energy along the transmission line for profiling the emulsion layer.