Abstract: A passthrough method is provided in which the surface of an industrial grade, low-grease precursor made of copper, with a defined surface roughness, is patinated. For this purpose the precursor material, connected as the anode, is passed through an electrolysis bath, containing sodium carbonate and/or sodium hydrogencarbonate as well as sodium sulfite and/or sodium disulfite, with a temperature of 30.degree. C. to 90.degree. C. and a current density of 1 A/dm.sup.2 to 20 A/dm.sup.2 as bath parameters, for a residence time of 10 seconds to 12 minutes. The precursor material is rinsed and then moved through a fixing bath at a temperature of 35.degree. C. to 95.degree. C. for a residence time of 10 seconds to 120 seconds, and lastly, after a further rinsing, is dried. The fixing bath contains at least one of the oxidation agents: hydrogen peroxide (H.sub.2 O.sub.2), potassium chlorate (KClO.sub.3), potassium peroxodisulfate (K.sub.2 S.sub.2 O.sub.8), potassium permanganate (KMnO.sub.4), of copper sulfate (CuSO.

Abstract: A method for producing a uniform and adherent brown covering layer (brown patina) on surfaces of semifinished products made of copper, particularly on rolled tapes or sheets used in building construction. The surface of the copper semifinished product is first roughened by means of a mechanical treatment. The copper semifinished product is then heat treated at a temperature lying within the temperature range of 150.degree. to 650.degree. C. for the duration of 0.1 to 30 minutes. The copper semifinished product can be advantageously subjected to a chemical postoxidation treatment immediately following the heat treatment.