Abstract: A spray gun is provided, which comprises a twin fluid atomizing nozzle which atomises a process fluid by interaction with a driving fluid. The nozzle including a driving fluid passage having a driving fluid inlet, a driving fluid outlet, and a throat portion intermediate the driving fluid inlet and driving fluid outlet. The throat portion has a cross sectional area which is less than that of both the driving fluid inlet and the driving fluid outlet. The nozzle also includes a process fluid outlet located at, or downstream of, the driving fluid throat. The spray gun further comprises a flow adjustment device connectable to supplies of the driving and process fluids. The flow adjustment device is adapted to selectively vary the ratio of the process fluid to driving fluid supplied to the nozzle. A mist-generating apparatus incorporates this spray gun is also provided.