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I've just sprayed 4 coats of KTM - 9 (water based) on my guitar, then sanded with 400 grit, then another 5 or so coats. Good even thickness, if a little orange - peely. But I think I'll be able to level that.

Here's the question. On several areas where the binding/purfling meets the top, and in the rosette, there is a visible, if extremely fine gap. This gap was not visible before finishing, and even after a wash coat of shellac. Is this typical? What's the remedy, to provide a continuous, glassy finish. Shall I use a very fine brush to apply some finish to those areas, let harden (several weeks) then sand back? Finish at normal thickness, or thin with Denatured Alcohol? Thanks.

Filling those gaps is all part of the finishing process. Most call it "drop filling" where you can use a fine artist brush to just drop a drip of finish in the gaps. Let it cure (a week should be fine) then do a final level and rub out.

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Thanks, Rod! Delighted to know it's nothing unusual. I'll let you know how it goes.

As a sprayed finish "levels" while it dries, it tends to find those gaps and seeps into them somewhat. Also, if the gap is small, the finish will bridge it and after you sand the gaps will re-appear.
I drop fill with full strength finish. Most finishes shrink and when you dilute them, you reduce the solid content which may require more drop filling.

This is all based on my limited experience as I've only sprayed and finished 5 or my guitars, the others were either finished by someone else or pad applied finish.

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"There's really no wrong way, as long as the results are what's desired." Charles Fox

"We have to constantly remind ourselves what we're doing....No Luthier is putting a man on the moon!" Harry Fleishman

"Generosity is always different in the eye of the person who didn't receive anything, but who wanted some." Waddy Thomson