A manually operated spray applicator to deposit plaster or the like against a wall surface in a spray pattern. There is a forward containing chamber for the plaster, a rear pressurizing chamber to supply the pressurized air through a discharge stem, and an intermediate positioning chamber having a moveable...http://www.google.es/patents/US4961537?utm_source=gb-gplus-sharePatente US4961537 - Pressure operated spray applicator
