Letter 24056

Polishing of rhodium plated mirror

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I have a WWII antiaircraft searchlight that has a rhodium plated mirror. What is the best way to polish this mirror?

Thank You,

Jule Elliott Elkin
Searchlight Ad Ventures - Lexington, South Carolina

Hi Jule,
there is no such thing as polishing rhodium in the conventional sense. Rhodium is extremely hard and durable. Even with high speed polishing equipment using specialty compounds used for platinum group metals, rhodium is not affected much by polishing.

The best you can do is remove the rhodium mechanically, repolish the base metal, nickel plate and replate the surface over with rhodium. Obviously this will not be easy or cheap to do because of its size and the inherent technical difficulties. WW2 search lights used a rhodium process designed specifically for searchlights and many were scrapped during manufacturing because electroplating something that large even with custom anodes still yielded poor results.

Bear in mind money was no object when they were originally made! Your best bet would be to brush plate (selective plating)the new rhodium plating onto the refurbished surface area. There are a few aerospace platers who might be able to help.

Good luck, Dave

David Vinson Metal Arts Specialties Leonard, Michigan