A liquid formulation with uniform consistency over extended periods of time, said method comprising the steps of: providing a liquid formulation in a container, said liquid formulation having a viscosity greater than five centipoise; driving, by means of a power source, a piezoelectric actuator which is coupled to an orifice plate so that the piezoelectric actuator vibrates said plate to produce and disperse fine droplets of said liquid formulation, said plate being formed with orifices having diameters in the range of 1-25 microns; said piezoelectric actuator operating in a bending mode; and during vibration of said plate, delivering said liquid formulation from said container to said plate by capillary action.