Abstract: Apparatus and method for the fusion processing of synthetic thermoplastic resinous materials, utilizing a first high-velocity stream of gas to transport the resinous material through an elongated passageway which directs the stream of gas and transported material onto a workpiece, thereby fusing the resinous material. The elongated passageway is defined by at least one wall having a plurality of foramina or pores through which a second stream of gas is directed to heat the resinous material to a fusion temperature and to provide a slip stream on the inner surface of the wall thereby preventing the resinous material from sticking to the surface. The first stream of gas may be heated to initiate or supplement the heating of the resinous material.