An air-cap nozzle 103b for discharging an atomising air jet 101b for atomising paint from a spray gun, the air cap nozzle comprising a tip surface having an atomizing air outlet 100b and a rim region 102b surrounding the outlet. The rim region 102b comprises a continuous serrated portion formed by a plurality of protrusions 104 that protrude axially outward from the rim region 100b of the tip surface. The protrusions 104 are separated by valleys 105 configured to permit entrainment of ambient air by the atomising air jet 101b, the entrained ambient air being drawn through the valleys. The permitted entrainment provides mixing between the entrained ambient air and the atomising air jet 101b.