A spraying apparatus for spraying liquid surface treatment material which includes a gas inlet, a liquid inlet and an outlet nozzle. The apparatus also has a needle valve for regulating the supply of surface treatment material to the nozzle. The needle valve is at least partially located within a gas outlet chamber and is adapted so as to cause minimal disruption to the gas flow from the gas inlet to the nozzle. To further aid gas flow efficiency, the gas supply passage is substantially straight, the outlet chamber has a laterally outwardly tapering inlet and an inwardly tapering outlet and a smooth radius of curvature from the gas supply passage into the outlet chamber. There is also provided a control means for controlling the axial movement of the needle valve, the control means being provided with indicator means so as to provide an accurate, repeatable control means.