An exhaust stack system for a muffler having an exhaust stub pipe including a self-holding taper on the outer diameter of the exhaust stub pipe. The perforations are disposed along a circumference disposed concentrically with, and between, the central bore and the periphery. A two-segment lever extends between the base and a catch which is pivotably mounted to the base. By adjusting amplitude and frequency of a superimposed AC potential charged particles will oscillate in the created AC field such that only small light particles will emerge from the iris diaphragmshutter for further transfer in the dose forming process. The functional material composed of fine coloring particles, exhibits not only an excellent transparency but also a high tinting strength and a clear hue.