I was taught that you can slowly oxidize silver by leaving it in a
"ziploc" bag with a hard boiled egg. I've never done this, since I
prefer sparkle, but I have recommended it to customers. I assumed
that the sulfur in the egg acted much as liver of sulfur does. But
the fact that the oxidation "washed right off" is disappointing--I
guess I'll stop recommending it.
I used to immerse my naked but bejeweled body in a lot of natural
hot springs (those were the days when I had a life!) and my sliver
would be black when I got out. But I needed to use polish to bring
back the luster. I don't know why this would be different (sulfur is
sulfur, right?), but I'm sure at least a dozen other Orchidians can
explain the chemistry behind this!