Roby,
That's good advice.
However, If choosing to use or stay with automotive primer and automotive paint products, testing on panels isn't necessary.
The stuff works, sticks, and is basically thought free. Read the can or ask the tech guys. Simple as that.
Thing is, individuals have a tendency to re-invent the wheel, that is, with new products. Especially the latex stuff.
I'm not old school. I've been pulling the trigger on spray guns and air brushes for almost 4 decades. That's 40 years.I did this as aprofessional. This means I did it for money, actually my living, so the work had to be done right.
Art, graphics, custom paint, airbrush flames, on vans, motorcycles, boats, truck lettering and graphics. I did all the stuff you see on TV today but we had no TV shows then. We actually learned as we progressed.
It's all the same but different. Just because it's a model airplane, doesn't mean the application wouldn't be the same for, lets say, motorcycle tanks and fenders. It's just a surface, that'show I look at it.
There's a combination of many materials in these photos, including vinyl. All the painted art on canvas is with water base professional artist paint. I use Golden. Sometimes they get cleared.
Automotive paint is obvious in the photos and most is finished in a clear coat, especially the painted graphics "logos" for the WWF. I did the WWF'sairbrush art and graphics for quite a few years. Maybe 30 some odd trucks. This was back in the 80's.
I'm old, not dead!