Cyanide Reduction in Bright Stripping Using an Electrolytic Process. 1994.

TURI Technical Report No. 18. The Robbins Company, located in Attleboro, Massachusetts is a manufacturer of recognition awards. The manufacturing process involves metal plating and finishing operations for producing emblematic jewelry. One process in the metal finishing operation, bright stripping; better known in the industry as "bombing"; removes the surface oxidation and fire-scale from metal substrates. Typically, this is accomplished by immersing the substrates in a mixture of two hazardous chemicals, hydrogen peroxide and sodium cyanide, which generates a powerful, and dangerous, chemical reaction. This project investigates electrolytic bright stripping as an alternative technology to chemical stripping. It was found that using different electrolyte solutions for specific substrate compositions gave great results on gold alloys, copper, brass, and silver . We experimented mostly with a gold alloy electrolyte which after some modifications also gave us acceptable results with brass substrates as well. We are now successfully electrolytically stripping approximately 85% of the substrates that were once exclusively stripped by the use of chemicals. Worker safety has also improved due to the use of a less toxic and more controllable technology. The results of implementing this technology at The Robbins Company has proved it to be effective, economically feasible, and capable of reducing the use of hydrogen peroxide and sodium cyanide.

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