tingjunkie wrote:Can't comment on the chemistry or science, but the traditional wisdom assumes the foam carries the dirty stuff you don't want to drink, and that's why you're supposed to swipe it off with the gaiwan/teapot lid and get rid of it.
My teacher calls it "the breath of microbes", though from where I am sitting, I can't help but imagine millions of little critters drowning in a sea of boiling doom!
I am reading a book on tea and teaware from China, with English alongside the Chinese. They talk a bit about the foam, saying that in competitions way back when foam color and consistency were among the aspects judged. Apparently, white foam is a good thing, though I have never noticed a different color.