Process for producing a color and/or effect coating system on a substrate by applying an aqueous color and/or effect solid-color topcoat material or—alternatively—an aqueous color and/or effect basecoat material and a clearcoat material (wet-on-wet technique) to the substrate and curing the resultant coating films, which after curing have a water vapor permeability δ60° C.>6.0 mg/h·m·bar or p60° C.>286.4 g·100 μm/m2·d, where d stands for day, when the coating material contains no metal flake pigments; or have a water vapor permeability δ60° C.>4.0 mg/h·m·bar or p60° C.>190.92 g·100 μm/m2·d, when the coating material contains metal flake pigments.