A paint's film thickness decreases as they dry and give up their solvents by evaporation. Lacquer shrinks a lot, enamels a bit less, urethane enamels less, and Imron shrinks very little. Imron is epoxy based and hardens by chemical curing, not by evaporation. Powder coating is a plastic film that goes on as a dry dust and is fused by heat, shrinking very little to none. The art of spray painting includes knowing when to stop applying paint, when enough is enough.