Does copper migrate through silver?

COuld it have been extremely thin silver plating that has worn off with usage of the receptacle ?
Also silver tarnishes (silver sulphate) ... perhaps it's just tarnish you're seeing ? I don't think copper will migrate through silver at room temperature.

Psychicanimal, let me know what ever you find out. I've been using mine for about the some length of time with no discoloration.

what color is your fridge? after a similar burn in ( the equivilent of 27 years in duration) all my cryoed recepticals are now avocado. is there something sinister going on here? FWIW, we have a stainless steel sub-zero.

-cfb

Lighten up boys. There is some solid state diffusion that can occur in the copper/silver system but at room temperature I do not think you have enough time to wait for it to cause you a problem. If you continue to be worried, contact your University's metallurgy department for a phase diagram of the system and an explanation. What you report is surely an oxidation layer that can be easily removed.