Abstract: In a mould-pressing machine, atomizing nozzles with a vortex chamber deliver atomized liquid mixed with air through outlet apertures. The atomizing air nozzle or nozzles are constantly supplied with compressed air through a pressure conduit while the liquid nozzle solely receives liquid under pressure through a liquid channel and a slave valve controlled by the liquid pressure in the periods during which injection of liquid mist is desired. A first (upstream) vortex chamber is provided upstream of a second (downstream) vortex chamber, and between these two vortex chambers a flow path is provided to interconnect the two vortex chambers, through which flow path the liquid mist having been formed in the first vortex chamber is forced to pass and change its direction and velocity of flow at least one, thus reducing the droplet size of the liquid mist.