Full disclosure: I am still really new at all this, having just started in the last few months.
Before painting smaller pieces such as suspension and engine parts, I always do fitment tests and file or sand as needed to ensure a good fit. After painting, I occasionally experience fitment issues during final assembly, and I think the root cause is I might be overdoing it with the paint.
I primarily use lacquer-based primer and paint, and occassionally acrylics for hand-brushing. I almost always use 3 light primer coats, then 2-3 color coats. I never clear coat smaller parts.
Anyway… Does it sound like I may be using too many coats, or maybe laying them on too thick? I am not sure why I’m even using three primer coats on these parts. My inner voice is telling me if the part is adequately covered after one to two coats of primer, or paint for that matter, what good are the additional coats doing?
I most often do a single coat as long as it’s covered. Might take two. Some lacquers and enamel can go direct to plastic on the smaller parts. At any rate, I pretty much airbrush the entire kit right on the parts trees with Stynylrez primer, just one coat. Except the large beauty parts like car body or airplane fuselage, those I do separately to make sure I get what I want. I do brush paint primer on things like radiator hoses and such, as that will probably also be my top coat after some weathering.
Okay!
Now Hear This! If you have One color coat that covers the part completely, don’t paint it again. Yes’ paint will flow to the connector Pins or Grooves and fill them up making the job harder. Trick. Paint around those areas carefully first. Then finish it out.That way you don’t have to scrape paint either.
On later Model Cars or Other models that have Body panels that have to be the same color, then don’t paint the edges. Glue doesn’t like paint ! Be especially careful when Priming because this will fill locator holes and grooves!
I frequently do not prime very small parts, and I brush paint them (usually if different color than most parts on sprue). If it looks good it is good. Go by appearance. With brushing of enamel, one coat does it. With acrylic it usually requires two.