A CORE-FORMING WIRE, TO BE COVERED WITH METAL, IS CONTINUOUSLY DRAWN FIRST THROUGH A CIRCUMFERENTIAL MILLING DEVICE FOR SKIN REMOVAL AND THEN THROUGH AN AXIALLY OPERATING SHAVING AND PROTECTIVE DIE TO PROVIDE A VIRGIN SURFACE. FROM THE SHAVING DIE IT MOVES IN UNCONTAMINATED CONDITION INTO A BATH FOR APPLYING A METAL COVER OR SHEATH TO ITS SURFACE BY ELECTROPLATING, HOT-DIPPING, TINNING OR THE LIKE. THE CORE IS IN COVERED CONDITION AFTER LEAVING THE BATH AND AFTER SOLIDIFICATION OF THE SHEATHING MATERIAL IS PASSED THROUGH SUITABLE FINISHING MEANS. THE ELECTROPLATING, HOT-DIPPING OR TINNING OF CONTINUOUS LENGTHS OF CORE-FORMING METAL FOR FORMING A DIFFERENT METALLIC COATING OR SHEATH THEREON REQUIRES THAT THE CORE SURFACES BE VERY CLEAN. THIS IS PARTICULARLY TRUE IN THE CASE OF ALUMINUM WIRE REQUIRED TO BE ELECTROPLATED WITH COPPER, FOR ALUMINUM IS EXTREMELEY PRONE TO RAPID REOXIDATION IN AIR AFTER OXIDE REMOVAL. SUCH OXIDE ACTS AS A CONTAMINANT INTERFERING WITH APPLICATION OF A STAISFACTORY METAL COVERING. THUS THE INVENTION IS PARTICULARLY USEFUL FOR IMPROVEDLY ELECTROPLATING A COPPER SHEATH ON AN ALUMINUM CORE WIRE BUT IT IS ALSO USEFUL FOR OTHER COMBINATIONS OF CORE AND COVERING METALS EMPLOYING HOT-DIPPING, TINNING OR THE LIKE.