Abstract: A multiple material spray system and method are provided for applying a spray by a single component spray gun. A first material is fed through a tube injector connected to an external port of the single component spray gun and a conventional fluid section feeds a second material through the single component spray gun without being exposed to the first material. A mixing area is positioned to receive the first and second materials outside of the single component spray gun so that these materials can be externally mixed immediately before applying a spray. The external mixing of the materials permits a spray of high viscosity, low VOC materials with fast gel times of approximately 20 to 40 seconds to be used because gelation in the single component spray gun is prevented by the external mixing. Also, the system and method reduce the number of components so that a more cost-effective process is achieved.

Abstract: By embodying a feed screw (17) for glass fiber reinforced polyester material with a hollow shaft, it is possible for the injection piston (11) for an injection unit (9) to have a compact structure so as to be passed through the feed screw (17). To process even viscous polyester compositions gently, the injection piston can be equipped with a plasticizer screw and an associated plasticizer motor.