Abstract: There is provided a method for forming a brilliant coating film with an excellent brilliant appearance by using aqueous first and second base coating compositions without preheating the applied first base coating composition. In the method, the aqueous first base coating composition is applied to a substrate to form a first base coating, the aqueous second base coating composition is applied to the first base coating to form a second base coating, a clear coating composition is applied to the second base coating to form a clear coating, and then the uncured coatings formed are simultaneously heated and cured, under controlling the solid contents of the first and second base coating compositions and the ratio therebetween, or the brilliant pigment mass concentrations of the base coating compositions and the ratio therebetween, or the mass ratio, the evaporation rate, and the solubility parameter of a solvent contained in the first base coating composition.

Abstract: An object of the present invention is to provide a coating film formation process which enables the formation of a coating film excellent in the metal-tone aesthetic appearance and the invisibility of aluminum flakes.

Abstract: A water base paint composition containing a mica-containing pigment(s), said composition comprising a water base paint containing a water soluble or water dispersion film-forming polymer selected from among acrylic resin, polyester resin, alkyd resin and polyurethane resin, a cross-linking agent and optional additives such as pigments, thickeners, fillers, etc., wherein a mica-containing pigment(s) comprised of mica flakes or metal-oxide-coated mica flakes with a surface acid content of 0-10 micromol/g, a surface base content of 0-30 micromol/g and a heat of water wetting of 0-1.5 J/g, the surface of which pigment being uniformly coated with melamine resin which has at least one triazine ring per molecule, is uniformly dispersed in said water base paint.