You have sanded till you're cross eyed.You have wet sanded till your fingers are wrinkled. Okay, then why do you still have rough spots here and there .No, not obvious ones,but ones that show up as soon as you apply paint! Here's a trick, Take some pencil lead you've sanded from a pencil, a number two works best. You take this powder you've allowed to drop on a Kleenex. After sanding the primer,You then rub the whole model with it.
Now, what do you see? You see a dark-grayish surface, with a few black blemishes in it . Those dark blemishes or " Pimples" are the blemishes your eye or fingers failed to find . This means ,of course you've got some more work to do .Guess what? You don't have a difficult step ahead.
Really! You go to the pharmacy and get the coarsest toothpaste ( yes, toothpaste,not Gel! ) This will then , using " Q " tips will be your sanding compound and the compound applicator too ! After you find you are not getting fuzzies and every nook and cranny has the same semi - gloss finish ,you are ready for the topcoats .I am sure you've rinsed and let the model air-dry,right ?
Well,there you have another way of getting that perfect paint - job. T.B.