Abstract: A coating system utilizing application under vacuum technology in which entrance and exit ports for the material to be coated are defined by a pair of horizontal gates and a pair of vertical gates at the inlet and outlet apertures of the coating chamber. A mounting arrangement at each port mounts the top vertical gate and the two horizontal gates in sliding relation with associated edges of the inlet and outlet apertures. Positioning arrangements are provided for each of the slidably mounted gates for setting an initial position of the associated gate, and each gate is provided with spring means for biasing that gate toward its initial position.