Dog Ma wrote:
> It would be more likely if
> the pot used for brewing is also used for boiling, hence exposed to
> direct heat that would enhance polymerization and bonding of the
> carbonaceous film to the cast iron.

I thought of that myself lately, something like keeping some strong
brew in the tetsubin, day after day, all day long, allowing the water
to evaporate over time.
It also depends on the actual water quality, content and composition of
minerals yadda yadda. Right now I´m still on the border of
Ostfriesland/Germania, with pretty soft (charcoal filtered tap-) water
(great for Assam based Ostfriesen Blends, baaaaad for DJs) and my
teawares stay relatively clean, whereas for example the tapwater in
Darjeeling is fairly rich in minerals and I see stains of any kind
develop quite rapidly, while basically brewing the same amount of the
same teas.

Dog Ma, it´s been a while ago for me but adressing polymerisation,
maybe you or someone else knows if the presence of iron ions helps in
forming insoluble complexes with the goodies (polyphenols) present in
tea ?

That brings up another question to the group:
what do your Yixing pots, especially yer older ones look like on the
inside (Oolongs/Pu-Erhs/...) ?

Karsten [time for the sack over here]





DogMa wrote:
> Dominic T. wrote:
> > ... All of mine are unglazed (glazed tend to crack internally no
> > matter how much care is taken). ... they build up deposits (which
> > many Japanese see as a good thing), they rust, ...
>
> I wouldn't use a glazed one; when the glaze chips off, it might wind up
> in my gullet. I do have a big one that sits on the wood stove in winter;
> I rarely pour from it, but it's nice to know that hot water's always to
> hand.
>
> On the latter point: I wonder if, with regular brewing use, a coherent
> organic film might form and passivate the iron surface? This certainly
> happens with other cast-iron cookware, and is why a seasoned pot or pan
> shouldn't be scrubbed down to clean metal. It would be more likely if
> the pot used for brewing is also used for boiling, hence exposed to
> direct heat that would enhance polymerization and bonding of the
> carbonaceous film to the cast iron.
>
> -DM