An aqueous coating material comprising at least one epoxy resin as binder and at least one polyamine as curing agent, wherein said epoxy resin or at least one of the epoxy resins (i) is solid per se at room temperature and/or is present in a powder coating material, and (ii) the solid epoxy resin and/or the epoxy resin powder coating material is or are present in fine dispersion in an aqueous dispersion comprising the polyamine or polyamines; and the use of the aqueous coating material to produce antistonechip primers.