I recall reading a science article where someone used a can of Pepsi and a 9-volt battery to put rainbow colors on stainless steel. If I remember correctly, some alloy in the can transferred to the steel through electrolysis, leaving a deposit only a few molecules thick. The article referred to the outer cladding metal on the Guggenheim Museum, and that it was done using the same principle, but on an industrial scale. Maybe I mis-remember the facts, but if you're good at researching on the computer, you ought to be able to find information on that. When the rainbow-colored pocketknives hit the market, I assumed that they were done by some electrolysis method. Good luck.