i don't know about plastic, but i have built resin kits before.
i used the tamiya gray primer out of a can. this stuff sticks really well to the resin peices. even if you try to scratch it, it won't come easily. not even if sanded down.
but i don't like spray cans. it always comes out bumpy and distorted for me. it always looks like dried up craters or something. and i don't like wasting time sanding everything down. even though this stuff adheres amazingly.
is there a primer that comes in a bottle that i can airbrush?
and what exactly is a primer? is it the same thing is a first painted coat?
does it have to say "primer" on the product for it to be a primer?
even if i primed my kits, the paint came off pretty easily. so i'm not even sure if this stuff is worth it. maybe a good topcoat will protect the paint better. if you spray it on more than one coat that is.