Gloss coat?? You'll love Polyscale clears. Thin with Testors Acrylic thinner a little less than 50% thinner. 18-22 psi and go thick and heavy coat, just before it starts to run. Goes on nice and glossy the first time. Let dry 2 days to be sure. With a flat coat, thin it less, and mist it on in thin coats. Too bad they quit making this stuff. All I can find is the Gloss, and when its gone its gone.