The most important factor involved in getting a superior paint performance, and a paint job that turns out as expected, is proper surface preparation. Primers and finish coats must be compatible for them to work together. When the painted surface is not properly prepared, or is primed with an incompatible primer, the final finish coats will not dry properly to a smooth finish. One of the biggest categories affecting finish coat performance is the compatibility, or lack of compatibility of the primers and finish coats.
Paint Product Compatibility
There are three major types of spray paint products. Acrylic, or acrylic enamel paints are heavy bodied, high solid content paints. The film thickness of an acrylic enamel paint is much thicker than the paint film thickness of enamel, or lacquer-based coatings. Enamel paints take longer to dry because the dryers are alkyd oil based, rather than acrylic. Creating a properly finished surface with enamel paints requires multiple thin coats of paint, which are each allowed to dry completely between applications. Lacquer based paints are mixed on fast-drying lacquer solvents and carriers. Lacquer paints and clear finishes go on thin, and dry completely in much less time than either of the two previous formulation paints.
Painted Surface Preparation
When applying paint, the surface must be properly prepared before the paint is applied. Any structural defects should be repaired. If repair products like plastic wood, fillers, fiberglass or bondo are used, these materials must be completely dry before the paint can be applied. If these products haven't cured, and any solvents from the repair products are trapped by the primer or finish paint, the solvents will push the paint off the surface as it evaporates.
Lacquer sprays on in a very thin mil coating. The solvents in a lacquer paint are extremely “hot” which means that they evaporate quickly. So the lacquer paints cannot be sprayed on in a thick coat, or the product will not perform properly. Lacquer paints dry to a hard shell, leaving a very thin paint film. For these reasons, lacquer is a good undercoat for any other paint product. Lacquer can be over-coated with other lacquer, paints, or enamels and acrylics.
Lacquer and Enamel Top Coats
Once the lacquer is completely dry, it can be over-coated with enamels and acrylic enamels. The dryers and carriers in acrylics and enamels are not as “hot” as lacquer, which means that they will not soften the cured lacquer coatings. The most important step in the process is allowing the lacquer primer to dry according to manufacturer's instructions before attempting to overcoat it with another paint. The enamel paints should be applied in thin coats, giving each a chance to dry before putting on a second, or third coat.