This invention relates to a method for forming a multi-layer coating,
comprising sequentially applying a layer of primer coating composition, a
layer of base coat composition, and a layer of clear coat composition on
an automotive substrate in a wet-on-wet-on-wet manner, and simultaneously
curing the applied three layers together in a single baking step. The
primer surfacer comprises a film forming binder, a volatile organic
liquid carrier, and pigment(s); and the binder contains about (a) 40 to
95% by weight of a caprolactone-modified highly branched acrylic polymer
having a hydroxyl and/or carboxyl monomer content, all or part of which
has been reacted with caprolactone, of about 1 to 65% by weight and a
weight average molecular weight of about 10,000 to 150,000; and (b) 5 to
60% by weight of an aminoplast resin crosslinking agent. The composition
is essentially free of crosslinked nonaqueous dispersion resin particles
or crosslinked microgel resin particles or both. The resulting cured
multi-layered coating has excellent aesthetic appearance, strike-in
resistance, chipping resistance, sag resistance, and film build even when
formed in a three wet layered application method.