FORMATION OF COATING FILM

PROBLEM TO BE SOLVED: To form a double coating film improved in finished coating film appearance and acid rain resistance. SOLUTION: In this foaming method of the coating film by applying a metallic or solid base coating material and further applying a 1st clear coating material and a 2nd clear coating material and baking them, the 1st clear coating material is a thermosetting clear coating material containing an acrylic resin, which is obtained by polymerizing a monomer containing a secondary hydroxyl group and has the OH value of at least 20 originating from the secondary hydroxyl group, and a melamine resin, 10-20wt.% of which has the number average molecular weight of 2000. Besides the 2nd clear coating material is a thermosetting clear coating material performing the reaction of a polyepoxy with a poly-acid, preferably the reaction of an acid anhydride modified group with an epoxy group, and the reaction of an acid anhydride group or the acid anhydride modified group with the epoxy group and the reaction of the acid anhydride group or the acid anhydride modified group with the hydroxyl group as the main reaction of hardening.