Tea (rec.drink.tea) Discussion relating to tea, the world's second most consumed beverage (after water), made by infusing or boiling the leaves of the tea plant (C. sinensis or close relatives) in water.

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Old 25-07-2005, 11:15 PM
erin jackson
 
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Default Teapots

I'm interested in purchasing a starter teapot. Does anyone
know what's the best type of pot to buy.

I've found several interesting ones on www.sunjaratea.com.
Love the look of the Staub Cast Iron, but would like to
see the tea. So is glass, porcelean or cast iron better.
..

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Old 26-07-2005, 03:40 PM
Scott Dorsey
 
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In article ,
erin jackson wrote:
I'm interested in purchasing a starter teapot. Does anyone
know what's the best type of pot to buy.

I've found several interesting ones on www.sunjaratea.com.
Love the look of the Staub Cast Iron, but would like to
see the tea. So is glass, porcelean or cast iron better.


I strongly recommend, if you have only one teaport, that you get
the Chatsford teapot in vitrified hotelware, which Upton's sells.

The spot is well-shaped and does not drip, and the hotelware is
much more difficult to break than glass, spatterware or porcelain.
It is not phenomenally elegant, but it is practical and reasonably
priced.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."
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Old 26-07-2005, 04:52 PM
Eric Jorgensen
 
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On Mon, 25 Jul 2005 22:15:47 GMT
erin jackson wrote:

I'm interested in purchasing a starter teapot. Does anyone
know what's the best type of pot to buy.

I've found several interesting ones on www.sunjaratea.com.
Love the look of the Staub Cast Iron, but would like to
see the tea. So is glass, porcelean or cast iron better.




You will probably end up owning more than one pot, and more than one
person will tell you to buy a Chatsford. Sometimes i wonder if someone has
an endorsement contract or something.

Cast iron pots are traditional for some japanese teas and have their
advantages but they also demand more maintenance. I have a small Kafuh
tetsubin i use from time to time.

Some will disagree with me but i don't believe there is anything at all
wrong with glass.

The decisive factors are going to be how well it pours, how easy it is
to clean, and whether the infuser design works the way you want it to.
There are pots good and bad in all available materials.

As for how well the spout pours, that's hard to determine visually. It's
something about how the lip on the end is formed. The only pot I've had
trouble with was more of a pitcher than a pot, and didn't have a regular
spout as such.

Don't personally own any porcelain pots, just various glass and metal.

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Old 26-07-2005, 08:19 PM
Scott Dorsey
 
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Eric Jorgensen wrote:

You will probably end up owning more than one pot, and more than one
person will tell you to buy a Chatsford. Sometimes i wonder if someone has
an endorsement contract or something.


I don't have an endorsement contract, but I did drop a Chatsford hotelware
pot ten feet onto concrete and it didn't break. Since I drop things
a lot, that's a big deal.

Needless to say the bone china ware is probably not so rugged.
--scott


--
"C'est un Nagra. C'est suisse, et tres, tres precis."
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Old 26-07-2005, 10:09 PM
aloninna
 
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As a starter I'd prefer something convenient rather than fancy.
Try IngenuiTEA at www.adagio.com



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Old 27-07-2005, 08:26 PM
Bluesea
 
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"erin jackson" wrote in message
...
I'm interested in purchasing a starter teapot. Does anyone
know what's the best type of pot to buy.

I've found several interesting ones on www.sunjaratea.com.
Love the look of the Staub Cast Iron, but would like to
see the tea. So is glass, porcelean or cast iron better.


Glass is better for viewing & easy cleaning - doesn't retain flavors and
aromas - just rinse, maybe a light brushing, with hot water.

Porcelain is better for heat retention - stains, flavors and aromas are
removed easily enough with a solution of baking soda and hot water and a bit
of brushing.

Iron is better for ...? Hmm...in general, metal dissipates heat faster than
earthenware and some swear that a metallic taste is added to the brew
although I don't know about cast iron in particular. May need to use a
potholder since metal handles are typically significantly hotter than glass
or porcelain.

Personally, since I'm a huge fan of both glass and Chatsford teapots, I
recommend either of those. One thing to consider if you're looking at Jenaer
teapots, is that they discontinued production this past March and won't be
available after the current stock is sold.

HTH.

--
~~Bluesea~~
Spam is great in musubi but not in email.
Please take out the trash before sending a direct reply.


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Old 27-07-2005, 08:48 PM
Bluesea
 
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"Eric Jorgensen" wrote in message
news:[email protected]

You will probably end up owning more than one pot, and more than one
person will tell you to buy a Chatsford. Sometimes i wonder if someone has
an endorsement contract or something.


Something! Those fine mesh infusers make brewing loose tea and clean-up
super-easy and the wide variety of design/size/material choices suit just
about everybody.

--
~~Bluesea~~
Spam is great in musubi but not in email.
Please take out the trash before sending a direct reply.


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Old 27-07-2005, 08:58 PM
Eric Jorgensen
 
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On Wed, 27 Jul 2005 14:26:05 -0500
"Bluesea" wrote:

Iron is better for ...? Hmm...in general, metal dissipates heat faster
than earthenware and some swear that a metallic taste is added to the
brew although I don't know about cast iron in particular. May need to use
a potholder since metal handles are typically significantly hotter than
glass or porcelain.



A proper tetsubin is porcelain glazed on the inside, and should add no
more flavor to your tea than a porcelain pot. It's typically a black glaze.

Metal does dissipate heat faster. The point of the cast iron pot,
however, is that you can pre-heat the pot by filling it with boiling water
for a few minutes, then dumping that water, adding the tea, and steeping.

Which will change the way the tea steeps and generally requires a
shorter steep time, fwiw, since the hot water loses less heat to the
pre-heated pot.

The cast iron has enough thermal mass that the pot will still be hot to
the touch 15 or more minutes later, so if you're going to be drinking the
tea over time you should steep with a bag or infuser (infuser should come
with the pot) and remove the tea after steeping.

Properly pre-heated, tea in my tetsubin stays hot far longer than tea in
any of my glass pots.

I do have one stainless steel pot, but the spout leaks so i haven't
used it yet. I know how to repair it, I just need a round tuit. I imagine
it loses heat very quickly. On the other hand, it certainly wouldn't object
to being placed over a candle-type warmer.

Oh, fwiw, never apply direct heat to a cast iron teapot. It will ruin
the finish. Only heat it by filling it with hot water. An electric mug
warmer would also be fine. No stove, no oven, no candles.

Always dry them thoroughly and allow them to sit upside-down with the
lid off in a warm, dry place for a few hours after use. The bits around the
openings where the glaze on the inside meets the patina on the outside can
rust up fairly quickly if the pot is lidded directly after hand-drying.
Humid air inside the pot will condense.

Never, ever, under any circumstances, clean any cast iron in a
dishwasher. Not even glazed LeCruisette cookware. Always hand wash. And in
the case of a tetsubin (and most bare cast iron cookware as well), don't
use any soap or detergent of any kind unless you actually need to. Go ahead
and use soap on enameled iron cookware, but dry it on the stove like any
other iron cookware.

- Eric "Cast Iron Chef" Jorgensen
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Old 27-07-2005, 09:15 PM
Scott Dorsey
 
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Clearly, this is not the kind to get:

http://www.msnbc.msn.com/id/8642038/
--scott


--
"C'est un Nagra. C'est suisse, et tres, tres precis."
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Old 27-07-2005, 09:22 PM
Bluesea
 
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"Eric Jorgensen" wrote in message
news:[email protected]
On Wed, 27 Jul 2005 14:26:05 -0500
"Bluesea" wrote:

Iron is better for ...? Hmm...in general, metal dissipates heat faster
than earthenware and some swear that a metallic taste is added to the
brew although I don't know about cast iron in particular. May need to

use
a potholder since metal handles are typically significantly hotter than
glass or porcelain.


excellent info snipped

Metal does dissipate heat faster. The point of the cast iron pot,
however, is that you can pre-heat the pot by filling it with boiling water
for a few minutes, then dumping that water, adding the tea, and steeping.

Properly pre-heated, tea in my tetsubin stays hot far longer than tea

in
any of my glass pots.

- Eric "Cast Iron Chef" Jorgensen


Thanks for the good info.

I thought preheating is SOP for all teapots (except the IngenuiTea) but this
sounds like you don't preheat your glass pots. Have you compared preheated
glass to preheated metal? I know that glass doesn't retain heat as well as
ceramic so wouldn't expect your tetsubin to be better than glass.

--
~~Bluesea~~
Spam is great in musubi but not in email.
Please take out the trash before sending a direct reply.




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Old 28-07-2005, 06:34 AM
Eric Jorgensen
 
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On Wed, 27 Jul 2005 15:22:18 -0500
"Bluesea" wrote:


"Eric Jorgensen" wrote in message
news:[email protected]
On Wed, 27 Jul 2005 14:26:05 -0500
"Bluesea" wrote:

Iron is better for ...? Hmm...in general, metal dissipates heat
faster than earthenware and some swear that a metallic taste is added
to the brew although I don't know about cast iron in particular. May
need to

use
a potholder since metal handles are typically significantly hotter
than glass or porcelain.


excellent info snipped

Metal does dissipate heat faster. The point of the cast iron pot,
however, is that you can pre-heat the pot by filling it with boiling
water for a few minutes, then dumping that water, adding the tea, and
steeping.

Properly pre-heated, tea in my tetsubin stays hot far longer than
tea

in
any of my glass pots.

- Eric "Cast Iron Chef" Jorgensen


Thanks for the good info.

I thought preheating is SOP for all teapots (except the IngenuiTea) but
this sounds like you don't preheat your glass pots. Have you compared
preheated glass to preheated metal? I know that glass doesn't retain heat
as well as ceramic so wouldn't expect your tetsubin to be better than
glass.



Ceramic is a better insulator than glass and a better insulator than
iron.

HOWEVER.

Most glass pots are borosilicate, most tetsubin are gray cast iron.

Thermal properties thereof:

Borosilicate Glass:

Mean Specific Heat: 910 Joules per kilogram-kelvin
Mean Thermal Conductivity: 1.3 Watts per Meter-Kelvin
Density: 2.23 Grams per Cubic Centimeter

Gray Cast Iron:

Mean Specific Heat: 440 Joules per kilogram-kelvin
Mean Thermal Conductivity: 80.2 Watts per Meter-Kelvin
Density: 7.87 Grams per Cubic Centimeter

Specific heat is defined as the amount of heat, expressed here in
Joules, per unit of mass required to raise the temperature one degree
kelvin.

With respect to the ability of a given solid to retain heat, it is
generally accepted that solids release heat at the same rate they absorb
it, all things being equal, and assuming spherical horses on an infinite
plane.

Radiation and conduction have their effects, but lets assume for the
moment that the air is still and both pots sit on an asbestos trivet.

Air, treated as either a fluid or a gas, in general, is a slightly
better insulator than glass, it just has wacky-variable density determined
by heat and pressure.

If you want to figure out the convection due to expansion of air heated
both by conduction and radiation, I can give you some numbers to work
with, but you'll never finish working out the math without setting up a
cluster of computers to model the currents of heated air through the
unheated air. And I'm pretty sure that granted the similar surface area of
the pots, the margin of difference in dissipation we're dealing with
renders those results largely meaningless.

Thermal conductivity here is expressed as the heat flow rate (measured
in watts) times the distance divided by an area per temperature gradient,
in this case meters per degrees kelvin. This is how fast heat moves through
a solid.

Density, of course, is expressed here as how much it weighs vs. how big
it is.

So we can see that given an equivalent mass, it takes twice as much heat
to bring the glass pot up to temperature, but it also holds on to that heat
twice as long.

Additionally, an equivalent mass of iron will transmit heat throughout
it's volume more than 60 times faster than borosilicate glass.

The thermal conductivity of the glass does in fact class it as an
insulator where the iron is considered a good conductor of heat.

And you can see that the iron is significantly more dense than the
glass. Moreover, a typical borosilicate pot has very thin walls - 1mm or
less - whereas a typical tetsubin has wall thickness varying from 3 to 5mm.

My 600cc tetsubin - including handle - weighs 1359 grams, without
infuser or lid.

My 600cc borosilicate glass pot, without infuser or lid, but with
integrated handle, weighs 225 grams.

Both pots have a spout roughly 1.5 inches in length, with similar
diameter. The tetsubin is slightly more squat than the borosilicate pot.

For the sake of inquisition, the handle on the tetsubin is a long
front-to-back loop of steel that probably weighs 150 grams or more on it's
own, and the handle on the glass pot is a small side loop that probably
weighs several grams.

So for the sake of argument, lets be generous and say that the tetsubin
weighs 1.2kg.

For what it's worth, the thermal interface between the steel handle and
the cast iron vessel is quite small and quite poor, and the handle never
even gets warm.

THEREFO

Heated to the same temperature, and very roughly speaking, my
borosilicate glass pot is worth about 205 joules, and my tetsubin is worth
about 528 joules.

So, from the numbers above we can infer a few things.

1: A cast iron pot with a mass similar to the borosilicate pot would be
bloody worthless, having quite poor thermal mass and leaking heat to
everything that touches it. It would probably also be quite flimsy, as it
would have to have much thinner walls. Something like an inflated balloon.

2: The truth is that with almost 5 times the mass, even though it's got
half the heat, gram for gram, it's still got more than two and a half
times the stored energy to go around.

3: A borosilicate glass pot with a mass similar to the iron for an
equal interior volume would be superior to the iron, but would have walls
almost 1cm thick, and take a very long time to preheat.

4: A similar mass of aluminum, pre-heated, with a specific heat of 900
k/kg-k would have them both beat. But it would have absurdly thick walls,
and the available array of anodized colors would be no match for the earthy
aesthetics of cast iron with a good patina, or the simple serenity of a
well formed glass semi-sphere.

5: A similar mass of 440 stainless steel, with a specific heat of 460, a
thermal conductivity of 24, and a density of 7.65, would heat slower than
the iron but hold the heat about the same. It would unfortunately be
prohibitively hard to make, and as such most stainless pots have
significantly less mass than their cast iron brethren.


Thus, it is both my considered opinion and my observation that while
preheating a paper-thin borosilicate glass pot is almost entirely
pointless, pre-heating a cast iron pot before steeping is not only
beneficial but required.

Pyrex, fwiw, has a similar specific temperature and poorer conductivity
as compared to borosilicate.

And furthermore, owing to the greater thermal mass in the iron, and
assuming a poor thermal interface with the trivet, tea inside a preheated
tetsubin will stay hot roughly twice as long as tea inside a preheated
borosilicate pot.

QED.

Anybody got numbers for the specific heat, thermal conductivity, and
density of popular ceramics?
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Old 28-07-2005, 07:57 AM
danube
 
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Anybody got numbers for the specific heat, thermal conductivity, and
density of popular ceramics?


If you are worried about heat retention of a vessel, and you want to keep
the heat within the teapot for a long time, go for a thermoflask, made of
glass (it will be coated with reflective aluminium layers within the
vacuum space).

JB
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Old 28-07-2005, 10:02 AM
icetea
 
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tools of the trade
!the perfect set!
for your greens and whites--use a guywan to keep temp down.
oolongs -- use clay/yixing.
blacks -- porcelain ofcourselain.
pu-erhs -- stoneware.
flower/herb/flavored -- glass (Schott Jena Glas) this is good german
glass and wont break.

icetea
anyone have any other combos

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Old 28-07-2005, 10:29 AM
icetea
 
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if we look at the tried and tested teapots, we find good reason for
the choice of vessel used, porcelain will be used for teas that taste
better at lower temperatures and is just so happens it dissipates heat
quick. Also high brewing temperature black tea is best brewed in clay
pots because they hold the heat, excluding the english who just love
porcelain or silver for brewing everything. trial and error is how a
tea student approaches a new pot that will be used for their
examinations/or tea tasting. they will experiment with amount of tea,
time, and temp. of water (initial time) when we approach this question
infusion vessels, some times the empirical data is not what was
expected from a theoretical model
this is an interesting discussion, the science of tea brewing, as
opposed to the art of tea brewing.

icetea



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