A process is described for the manufacture of a dimensionally stable polyester film support carrying a primer coating for improving the adhesion thereto of subsequently applied coatings, which process comprises applying to an unstretched or only monoaxially stretched polyester film support a layer of a coating composition from an aqueous dispersion, drying said layer, stretching it biaxially or in a direction perpendicular to the said first stretching operation together with the polyester film support and heat-setting the polyester film, wherein said coating composition, before drying and heat-setting, comprises a mixture of:(A) 52 to 79% by weight of a copolymeric binder comprising 60 to 95% by weight of methyl methacrylate, 3 to 20% by weight of a divinyl or diallyl monomer, 0 to 30% by weight of a plasticizing vinyl monomer, and 0 to 5% by weight of an ethylenically unsaturated carboxylic acid,(B) 0.5 to 3% by weight of a water-insoluble wax-like material and/or of a water-insoluble polymer characterized by the presence of repeating units corresponding to the formula : ##STR1## wherein each of X, X.sup.1, X.sup.2, and X.sup.3 represents hydrogen or fluorine, or each of X, X.sup.1, and X.sup.2 represents hydrogen and X.sup.3 represents a methyl group, or X represents chlorine and each of X.sup.1, X.sup.2, and X.sup.3 represents fluorine,(C) 20 to 40% by weight of an external plasticizer, said external plasticizer being wholly or almost entirely eliminated from the coating composition during the heat-setting, and(D) 0 to 5% by weight of a hydrophilic polymer.