The present invention relates to an article comprising a polymer substrate and a co-extruded polymer coating. The polymer substrate is for example manufactured from a thermoset rubber, a styrene based thermoplastic elastomer, an olefinic based thermoplastic elastomer or mixtures of these polymers. The co-extruded coating comprises an optical brightener for example a fluorescent agent. The co-extruded coating for example has a thickness smaller than 700 micrometer. The article is for example used in automotive applications, in building and construction applications, in packaging, in food applications, consumer applications, in medical applications or in wire and cable applications. The present invention also relates to the use of the articles of the present invention in automotive sealing systems.