Disclosed herein is a core-shell graft copolymer produced by coagulation of an aqueous latex comprising a quantity of particles of the copolymer and a quantity of a fatty acid surfactant, wherein the coagulation involves the addition of a quantity of a multivalent metal salt, preferably a bivalent or trivalent metal salt. Such copolymer provides in an improvement of the surface properties of moulded articles produced from such copolymers, as demonstrated by a reduction of the content of gels in the surface layer.