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...addition
Air curing finishes create a skin on top by oxidising the top layer, once this happens it is soluble in the solvents used in the finish. This creates a bag of wet varnish and causes these problems. A thin coat is about the thickness of the "bag" lets the oxidation happen through the whole layer.

Two pack finishes react with themselves through the layer, no problem. Similarly with solvent drying ones (like cellulose lacquer) let the solvent out by partially dissolving the (now semi dry) top coat.

Dip "painting" tends to level all the variables out and works well, that is if you have enough to make a dip bath! As an aside (nearly) take a look at spin coating, despite the surface spinning at a low velocity at the centre and quickly at the perimeter an even coat is formed, the maths is involved, the result rather clever.