On Apr 20, 7:53*am, "No Body" wrote:
* * I have two pieces, both made by me 30 years ago; one is a copper-foil
window and the solder is as shiny as the day it was made. The other is a
lamp with zinc came soldered together and it is grey and dull, both zinc
aznd solder alike. Any ideas why the difference?

The lead in the solder can react to the zinc. It's called galvanic
reaction. It's caused by moisture, perhaps humidity, bridging from the
solder (which has the lead in it) to the zinc. Zinc over time will
also get dull just by it's self. You should be able shine it up with
some #0000 steel wool.