A method of texturing a wall or ceiling with non-acoustical joint compound by providing a collapsible bag having an opening at its top and is adapted to contain non-acoustical joint compound for forming a textured coating on the wall or ceiling and providing a spray nozzle having a low pressure input port, a joint compound suction port attached to the opening at the top of the collapsible bag, and an output port for spraying the non-acoustical joint compound. A low pressure stream of air from an air gun attached to the low pressure input port urges a small quantity of the non-acoustical joint compound to be sprayed out of the spray nozzle when the bottom of the collapsible disposable bag is raised above its top to either allow or force the joint compound to flow into the suction port and into the interior of the spray nozzle.