A method and apparatus is disclosed, in the presently preferred embodiment, for applying powdered adhesive to non-woven fabric material. The apparatus includes a novel powder spray gun wherein there is an air flow amplifier contained within the gun for accelerating the velocity of powder emitted from the gun and sprayed onto the top of a conveyorized web of the fabric material. The apparatus also includes a novel system for supplying powder to the spray gun, which system includes a first powder pump, a back-up pump and a control circuit responsive to detection of reduced powder flow to the gun to switch supply from the first pump to the back-up pump.