ENAMEL BRUSH-ON

No, it was Testors Spray Enamel Metallic Silver, so it was an enamel over an enamel

Not a very good Idea I am afraid. I doubt you would have been satisfied with the result even had you airbrushed boat coats of paint on. I would suggest a different technique. For instance. Brush on (or preferably airbrush on) the interior green color, then, when it has dried, dry brush the interior with testor's silver. While there is still a little wet silver pain in the brush, smash the brush down on the floor boards and other high wear areas to simulate exposed bair metal. Do practice first as the main mistake people make who are new to this is to start with a brush that hold too much paint (wet paint). I usually blot and wipe my brush on an ixdex card until hardly any sliver paint is being left on the index card.

WHat did you use for the silver base spray? Was it a buffing metallizer??

ANdy