Surface coating process where the workpiece through an anode-cathode reaction is coated with a thin decorative layer of hexavalent chrome with a black tone. Beskrivning The process Before processing can begin the work should have been pre-treated to achieve a clean surface, which is usually done through electrolytic cleaning followed by pickling and rinsing. The workpiece acts as a cathode and the surface coating agent acts as the anode when connected to a power source and immersed in a solution. The solution used in this method is a mixture of chromic acid and a catalyst that is dependent on the substrate to be coated. Having the sulfur solution kept at around 30°C the characteristic gray-black chromium coating is achieved. An anode-cathode reaction occurs which drives the chromium ions to the workpiece and create a layer of hexavalent chromium on the surface of the workpiece and increases its wear resistance and corrosion protection. Black chromate plating
