Inge:

  When Tin/Lead is plated, it really is not a true alloy, but in fact discrete crystals of Tin an Lead, and as such is much more prone to corrosion.  Tin tends to be self-protective, and forms Tin +4 oxides, which are quite insoluble, this leaves the Lead open to react.... perhaps slowly over time with the Carbon Dioxide in the air, or other cleaner residue?

  Tin/Lead when it is a true alloy is a solid solution, and you do not get this effect.

  Is it possible that this is why you are seeing it only on a single place, and not universally?

  My 0.015 Euros worth...

  Rudy Sedlak




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