Abstract: The invention provides apparatus for spray coating of substrates using a rotary bell cup atomizer equipped with an air-driven main turbine and a supply of pressurized primary shaping air conveyed through primary shaping air channels and nozzles for controlling the shape of the atomized spray pattern exiting the bell cup edge, the apparatus further including an auxiliary, independently air-driven turbine equipped with a rotatable vortex generator, and including a separate air supply of secondary shaping air for supplying secondary shaping air through secondary air channels and nozzles to further control the shape of the atomized spray pattern exiting the bell cup, which secondary shaping air, on passing through the vortex generator, produces a curtain of shaping air in a vortex-like pattern, which, in conjunction with and mixing with the primary shaping air from the primary air nozzles, produces improved pattern control, transfer efficiency and quality of coating on the substrate.