In a method for scanning the surface of metallic workpieces, during scanning, a welding torch with a consumable welding wire is moved over and towards the workpiece surface, until contact of the welding wire with the workpiece is detected, and the welding wire is subsequently moved away from the workpiece. Before scanning, slag-removal is carried out to remove slag at the welding wire end, wherein the welding current is lowered to a minimum, and the welding wire is moved cyclically with a rapid recurrent forward/backward movement over a specified path length toward the workpiece, and by a smaller distance away from the workpiece, until a short circuit between the welding wire and the workpiece is detected, whereupon slag-removal is ended, and upon the detection of no short circuit, slag-removal is repeated, and upon the detection of several short circuits one after the other, slag-removal is ended.