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Is rhodium-plated silver a good solution for nickel-itch?

     

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We recently found out that my soon-to-be-wife apparently has an nickel allergy. She had some nickel-posted ear-rings and boy did her ears swell and blister. Anyhow, she likes white gold or platinum colored jewerly but given that there is a chance that the white gold will bring on this nickel-itch, and Platinum is a bit high for us strving students I was thinking of geting her a rhodium-plated silver ring. Do we run the same risks in regards to a nickel reaction?

Stephen Emery
Consumer - Cambridge, Massachusetts

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Any non-porous barrier layer will temporarily prevent nickel itch, but it is not a long term solution. Unfortunately, the only long term solution is to avoid jewellery that contains nickel. In Europe this is easy - it is now illegal to sell nickel containing jewellery, so you will be safe with any new things here. However, that is not the case in the USA or the Far East. To prevent nickel itch re-occuring, the rhodium palting should be quite thick, say 5-10 microns; this will give you a good barrier alyer with long term wear resistance, but be aware it will have to be repeated in the future. Good luck.

Trevor Crichton R&D practical scientist The Pheasantries - Chesham, U.K.

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It is extremely difficult to electroplate rhodium (stress) crack-free, therefore the silver migrates right through the open galvanic cell with the rhodium and corrodes on top. High-reliability electronic components platers CAN plate crack-free, but most downtown job shops you can get to have a very dirty rhodium bath that plates with cracks.

So, specify palladium or platinum between the silver and rhodium to act as a difusion barrier.

Robert H Probert Robert H Probert Technical Services Garner, North Carolina Editor's note:        Mr. Probert is the    author of Aluminum How-To / Aluminio El Como