A valve assembly for an aerosol spray device, the assembly comprising: a housing with internal walls defining a valve chamber, the chamber having a liquid inlet (212, 214) for fluid communication with liquid in the aerosol spray device, and a gas inlet (234, 240, 244) for fluid communication with gas in the aerosol spray device; and a valve stem having proximal and distal ends, the proximal end received in the valve chamber and the distal end projecting through a sealed opening in the valve chamber, the valve stem including an outlet flow conduit with an outlet aperture at the distal end and, more proximally, at least one first stem inlet for liquid and at least one second stem inlet for gas; characterized in that the housing includes a lip projecting inwardly from the internal walls to form a seal around a perimeter of the valve stem along at least a portion of the valve stem, wherein the valve chamber liquid inlet is proximal of the lip and the valve chamber gas inlet is distal of the lip; wherein the valve stem is moveable between: a closed position in which the at least one first stem inlet is distal of the lip and the at least one second stem inlet is distal of the sealed opening in the valve chamber, such that the at least one first stem inlet is not in fluid communication with the valve chamber liquid inlet and such that the at least one second stem inlet is not in fluid communication with the valve chamber gas inlet; and an open position in which the at least one first stem inlet is proximal of the lip so as to be in fluid communication with the valve chamber liquid inlet, and the at least one second stem inlet is proximal of the sealed opening in the valve chamber and at least partially distal of the lip so as to be in fluid communication with the valve chamber gas inlet, whereby a bubble laden flow is created in the flow conduit. a housing with internal walls defining a valve chamber, the chamber having a liquid inlet (212, 214) for fluid communication with liquid in the aerosol spray device, and a gas inlet (234, 240, 244) for fluid communication with gas in the aerosol spray device; and a valve stem having proximal and distal ends, the proximal end received in the valve chamber and the distal end projecting through a sealed opening in the valve chamber, the valve stem including an outlet flow conduit with an outlet aperture at the distal end and, more proximally, at least one first stem inlet for liquid and at least one second stem inlet for gas; characterized in that the housing includes a lip projecting inwardly from the internal walls to form a seal around a perimeter of the valve stem along at least a portion of the valve stem, wherein the valve chamber liquid inlet is proximal of the lip and the valve chamber gas inlet is distal of the lip; wherein the valve stem is moveable between: a closed position in which the at least one first stem inlet is distal of the lip and the at least one second stem inlet is distal of the sealed opening in the valve chamber, such that the at least one first stem inlet is not in fluid communication with the valve chamber liquid inlet and such that the at least one second stem inlet is not in fluid communication with the valve chamber gas inlet; and an open position in which the at least one first stem inlet is proximal of the lip so as to be in fluid communication with the valve chamber liquid inlet, and the at least one second stem inlet is proximal of the sealed opening in the valve chamber and at least partially distal of the lip so as to be in fluid communication with the valve chamber gas inlet, whereby a bubble laden flow is created in the flow conduit. a closed position in which the at least one first stem inlet is distal of the lip and the at least one second stem inlet is distal of the sealed opening in the valve chamber, such that the at least one first stem inlet is not in fluid communication with the valve chamber liquid inlet and such that the at least one second stem inlet is not in fluid communication with the valve chamber gas inlet; and an open position in which the at least one first stem inlet is proximal of the lip so as to be in fluid communication with the valve chamber liquid inlet, and the at least one second stem inlet is proximal of the sealed opening in the valve chamber and at least partially distal of the lip so as to be in fluid communication with the valve chamber gas inlet, whereby a bubble laden flow is created in the flow conduit.