the present invention relates to a process for producing a multicoat paint system , in which an optionally pigmented basecoat is applied to a substrate surface , a polymer film is formed from the basecoat film applied in stage , one or more further coating films are applied optionally thereto , then a nonaqueous topcoat is applied which comprises a ) a hydroxy - functional polyacrylate resin , b ) as crosslinking agent tristriazine and c ) optionally further crosslinking agents , such as blocked isocyanates , which are different from the tristriazine , and / or amino resins , and subsequently the coating films are baked together , where in that the polyacrylate resin comprises secondary oh groups .