Purge method and apparatus for a manual spray gun or coating material application device, in which purge air is introduced into the device through a handgrip portion that is manually held during a coating operation. The circuit is a transmission line stub coupled to a fluidic dielectric and includes a composition processor for selectively varying a composition of the fluidic dielectric. An embodiment of the system also includes a communication interface coupled to the processor and coupled to a plurality of other investors by which the processor electronically places the at least one order. Part identification and tracking logic, gun triggering logic, gun movement logic, booth control logic, part profiling logic and system monitoring and logging logic may also be included. Specifically, polydextrose induced biphasic compositions have been unexpectedly found to induce such behavior.