Yes they still use these coatings on aircraft, industrial & chemical applications mostly because they stand up so well in tough environments and/or challenging adhesion. Aluminum is a particular bugger. I used Endura quite a bit in the past when we ran high nitro on the models, its a 2-part catalyzed system. You can still get it at Smith Mclay. Its nasty high Iso so you need proper PPG. You'd have to inquire if people are applying over raw metal. I suspect majority of their finishing application is the typical etcher/sealer/primer/color top coat & clear is generally intended for over color. Imron in the old days used to be somewhat similar to Endura but they have since reformulated it many times so I suspect its different now. Its getting harder to source this stuff for common mortals, many distributers just wont sell certain brands over the counter without some 'number' that basically says you are shop with approved air booth etc. Smith Mclay had a waiver form policy for a while but I think they dropped that & can purchase OTC.
Painting clear over metal is kind of a niche application. You can get all sorts of clears from auto paint suppliers that are intended for base/clear systems, also catalyzed, UV ingredients, flavors of shiny to matt. The trick is 'will it stick' as they are mostly intended to be over some underlying base coat (the color). I can't advise on those other products mentioned, never used them. You might want to Google some auto painting forums, especially FX painting because the 'old look' (bare metal, scratches, dents, rust) is kind of in vogue. But that crowd is very familiar with auto refinishing & I get the impression there are very specific products & preparation they use.
