A nozzle for a spray device comprising a mixing chamber (3) for a first fluid and a second fluid, said mixing chamber (3) having an exit orifice (24), an inlet feed (8) from an inner tubular passage (4) suitable for carrying the first fluid, and an inlet feed (5I) from an annular passage (5) surrounding the inner tubular passage (4) and suitable for carrying the second fluid, characterised in that the nozzle comprises a means for causing spiral flow around the inner tubular passage (4) of a fluid passing through the surrounding annular passage (5).