Hello everybody,
I had some silver medallions/tags cast for making engraved bracelets, and then had some of them rhodium plated and others gold plated (18k I was told).
I had read somewhere that the plating should be 3 microns thick to be lasting but I don’t know of any way to measure the layer after the process. So I started rubbing one of the gold plated medallions with a silver cleaning cloth, and the plating came off in 15-20 seconds!
Is that normal? Obviously you shouldn’t clean a plated medallion with that kind of cloth, but still… I did the same thing with a gold plated brass medallion I had bought and it didn’t rub off. Is this a case of "flash coating"? (meaning apparently an ultra thin plating that is less than 5 microinches thick)
1. How can obtain a better plating quality?
2. I know it depends mainly on 2 factors: the amount of gold in the bath, and the duration of the bath. What is the quantity and duration required to get a plating that is at least 1 micron thick?
3. Is there any way to test the quality of the plating?
4. I noticed some small marks on the plating and was told that it could be due to bubbles in the plating. Is there such a thing?
5. The are also some cloud-like marks on some of the pieces, any idea what could have caused that? Water stains? (I read this could happen)
6. Will applying some kind of coating over the plating increase it’s longevity?
7. Is it stupid to try and gold plate silver medals? Would gold plating brass produce much better and longer lasting results? (I consider brass jewelry as junk personally…)
8. What nickel free alloy is best suited as an underplate for gold plating silver (to avoid having the silver show when the yellow gold plating wears off)?

I really hope someone will be able to help me and sorry for all the questions
Thanks a lot