Bright metal surfaces electroplating

In electropolishing, the metal workpiece is made the anode rather than the cathode. Instead of deposition onto the surface of the workpiece, some of the metal dissolves, leaving a bright, polished surface. High points dissolve at a faster rate than recessed areas. Electropolishing is performed to improve adhesion of subsequent electroplates, to deburr and Finish parts, and for decorative purposes (Schaer 1971). 

On the other hand, many metals have characteristic bright, reflective surfaces that may be enhanced by polishing and surface treatments such as electroplating. The natural appearance of plastics is quite acceptable for many applications but sometimes there is need to make components with reflective surfaces similar to those in metals this may be no more than a question of appearance—the designer or manufacturer feeling that an item will look better—while in other circumstances a metallic finish may be functional. One instance of the second would be fittings for bathrooms, where a bright surface not only is attractive but also resistant to wear and easy to keep clean. 

The insensitivity of polyglycols to electrolytes makes them suitable as additives in electroplating baths. Even small additions of high molecular weight PEG in tin and copper plating ensure a solid bright metal deposit in the electroplating of aluminum, and stainless steel additions of PEG produce a very attractive surface [1121. 

Rhodium is one of the six platinum transition elements that include Ru, Rh, Pd, Os, Ir, and Pt. Of these metals, rhodium has the highest electrical and thermal conductivity. Although a relatively scarce metal, rhodium makes an excellent electroplated surface that is hard, wears well, and is permanently bright— ideal for plating the reflectors in automobile headlights. 

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