As I suggested before, the behavior of these things is consistant with the sort
of layered surface you get with a lack of control of fire scale and fire stain
in the original making of these. Your fix is simply to have them thoroughly
silver plated. Use a professional plating firm, so as to get a good thick
enough coating. The plated fine silver will be about as resistant to tarnish as
any silver surface could be. If you want better, get them gold plated. Same
deal. Use a pro. Thin gold plating may look good,The gold anode is only sacrificial in a cyanide based solution. In
other types, it's merely inert. The dip and plate electroless solutions put an
extremely thin layer on.