I borrowed the term throatiness from Lew, who was the first person I remember using this particular term. What it is supposed to mean is a sort of feeling in the throat when you drink a tea — some sort of coolness or tingly sensation. This is the kind of thing that usually only puerh has, but some other teas sometimes will have them too. Generally speaking, only good tea will have it and the longer and stronger it is, the better the tea is.
That is until I got my tetsubin. Now, oddly enough, almost all teas give off this sensation. Mind you, better teas still do better with longer/stronger feeling, but instead of just having that feeling once in a while, now I get it all the time, or at least most of the time. Of course, it might have to do with the fact that I’ve upgraded my tea drinking. I didn’t use to imbibe 20 years old oolongs regularly. In Beijing, and to a lesser extent Taipei, I was often drinking stuff that is no good for the sake of learning or experimenting. So obviously there is a bit of a sampling bias there. On the other hand, I have found that with teas that I know well, using the tetsubin will give me a stronger sensation of throatiness.
Is it some sort of chemical reaction, or the extraction/release of certain compounds through the addition of whatever it is that the tetsubin adds? I have no idea what it is, but it’s further proof that one can’t use only one or two criteria to judge a tea’s quality. So much depends on what you use to brew that tea, it is almost impossible to tell for certain what is causing the tea to taste a particular way.