I like the VJ Polyurethane primer, esp the US OD, which I use as a top-coat colour.
It does stick to Resin PE & plastic though, but I tend to spray in sub-assemblies
As said by many, it isn't very workable or sandable, unless you cut it with 15% +/- of Future/Kleer, which suits the way I work (your mileage may vary, test on something unimportant first, clove cover before striking, blah blah