I like my iced tea in the morning, and I've found that some blends are better for it than others. But the point of this thread is that some teas, when brewed and iced, leave me with an aftertaste that feels like I've been chewing on Zinc. Or at least drinking from a galvanized cup. Notably, Tazo (I avoid Starbucks for that reason, among others), Taylor's of Harrodgate, and Lifeboat (which looks and tastes suspiciously like Taylor's) leave that funny taste.
On the other hand, teas from Republic of, Mighty Leaf, Twinings, Teavana, Yumi, and Stash, don't ever seem to leave that aftertaste.
It doesn't seem to matter which blend or how I brew it. I've had that funny taste from Taylor's Ceylon, Assam, and regular (but for some reason not their Yorkshire Gold), and Tazo's black and oolong. But other people's Assams, Ceylons, and blacks don't seem to have that problem. I use consistent brewing, so I'm sure that's not it, and I've had Yumi and Taylor's brewed by other people using wildly different practices, with the same results.
So what is it?