"Space Cowboy" wrote:
> ... Some teas maintain their astringency after several
> infusions and for a few it even gets worse. That means the caffeine is
> still present while the taste is gone.

Astringency and bitterness are often associated, but need not be linked.
Slightly under-ripe persimmons taste fairly sweet but are extremely
astringent. Most alkaloids are very bitter, but not all are astringent.
Astringency ("drawing together" - literally, making the mouth pucker) is
separate from taste.

Tannins and the like can be very astringent, and extract relatively slowly.
Caffeine, which is very bitter, extracts rapidly and is not particularly
astringent. We ought to be more careful with nomenclature if we're going to
use it as a basis for ad-hominem attacks or to confuse newbies and others
who (at their own risk) seek authoritative and/or scientific knowledge.

-DM