Originally Posted by AiredAle
The green coating Reverend JC was concerned about wasn't an oxide. Copper oxides are black or red, not green. Some copper salts are used as insecticides, so I'd rather not have them in my beer. Also, while an oxide may be inert, some are soluble in acidic solutions, so you could end up with dissolved metal ions in said acidic solution, and again I don't want them in my beer for health and taste reasons. Copper oxides aren't an issue for us because they aren't soluble in wort, but are reduced back to metallic copper by the wort sugars, as I recall.
Yay for chemistry nerds! I have no idea what your words mean, but I think I used to... and I will think about it as I go to sleep tonight.
I'm more of a physics guy.
But it's all fun to think about....