I have been doing several experiments real world Paint on brass. The large sheet of brass used duplicolor etching primer and semigloss followed by pledge Floor polish. Between each coat 24 hours drying time.Final coat was Krylon Matte put on 8 hours after the decal. Looks decent but the floor polish is not the easiest airbrush. I actually get better results with a foam brush. I also tried Duplicolor gloss black which looked more like satin and had trace orange peal. No matter what I tried it did not come out gloss and had orange peal. The semi gloss on the other hand looked great and it’s somewhere between satin and flat. It also very temp and humidity tolerant...very forgiving paint like a true lacquer.
The smaller sheet of brass used Scalecoat one, an enamel, and was pretty easy to use out of the spray can directly on shiny brass as long as the environmental conditions are ok. Definitely passed the scratch test. It seems this is very sensitive to temperature. I would spray this in an environment less than 80 degrees F. High humidity here may be part of the problem. I did the one hour bake between 150-200 then waited 48 hours. I decaled then sprayed Krylon Matte 8 hours later. Acceptable result was obtained IMO.