Is poly that thick?

Raised panel wainscotting up the stairs at 39.6 angle. Dry fit had excellent joints at stile/rail point. Decided to finish outside rather than risk mucking up the house (I think this was a BAD idea, but SWMBO though otherwise.) Maple stain to make the QSWO match the red oak flooring and stair components went on first, followed by three coats of minwax gloss with light 220 between coats. Regular poly, not wipe-on. Now I have somewhat noticeable (1/16") gaps at the stile/rail points. The 16oz hammer didn't help, and I don't think the 2 pounder will do any better. I think the three coats of poly on the rails is causing the problem. It would be a bit of effort (well, a huge effort) to disassemble the panels and sand down the contact areas. Do y'all think that 3 coats of minwax gloss would cause this gap? Any other ideas?
FWIW, If I EVER do this again, I will either finish after assembly or refuse to take part in the task.
--
Jim Murphy,



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If you assume poly leaves a 3 mil thick finish per coat (a little thinner than regular paper), at 39 degrees and three coats on both sides, that's 0.028" (about a third of 1/16) offset due to poly.
Even at 1 mil per coat that would add up to 1/16 over 9 seams.
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Is it possible that the coating has built up at the edge? There is a technical term for this which escapes me right now, but this seems not unusual in my experience with enamel paint for finish carpentry in a house. Surface tension would tend to keep it from running around/over the edge.
Try a sample, and see if you can tell if this is an artifact of the self- leveling nature of these coatings.
Patriarch
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Just a thought...
How long was it outside? Was it humid?
(Get where I'm going here?)
J
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