Yixing

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Youzi
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Mon Jan 11, 2021 12:40 pm

@faj
Interesting. This means that if you put 100g of water at 100C in a 100g vessel preheated at 80C, the equilibrium temperature (excluding heat losses and the time it takes for that equilibrium to be reched) is about 85C.
No, the equilibrium temperature would be 96 degree. but at those temperatures it's not a linear thing anymore, so it'd probably be closer to 90.
It seems to me there is a way to cheat : if you are going to be brewing tea for several minutes and care for the temperature, you can perform a flash brew to preheat the teapot and leaves, pour that out, and add hot water again for the real infusion. The flash infusion is not going to cost much in terms of lost flavor (or else you would not need a long infusion), and you can still sip on it so there is no loss, really.
That's actually an awesome idea. Which further reinforces the need for lower mass teapots. As opposed to thicker heavier ones.
faj
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Mon Jan 11, 2021 12:42 pm

Youzi wrote:
Mon Jan 11, 2021 12:40 pm
No, the equilibrium temperature would be 96 degree. but at those temperatures it's not a linear thing anymore, so it'd probably be closer to 90.
Sorry for the brain cramp, you are right obviously, I will correct my post.

That being said, the non-linearity comes from the heat losses involved (it is an open system) and the time for these heat exchanges to occur. My post assumed these out, but in real life it will be lower as you mention.

Also, starting with dry leaves or wet leaves is not the same. Cold, wet leaves have a significant thermal inertia due to their water content, and due to the specific heat, 1g of water from the wet leaves does the same "damage" as 5g of clay (actually more as they cool water on contact, basically).
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Balthazar
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Mon Jan 11, 2021 12:59 pm

Youzi wrote:
Mon Jan 11, 2021 11:47 am
Based on my testing, unless you steep for really long times, over 6 minutes, heat retention doesn't really matter. Because it doesn't have enough time to take an effect, for 80% of a session, especially not at the beginning, which is the most important.
Agreed, I only really care about heat retention when I do "western brewing" or at the really late brews of gongfu cha (at which point I often opt to do a quick boil/simmer of the leaves instead)
faj wrote:
Mon Jan 11, 2021 12:18 pm
It seems to me there is a way to cheat : if you are going to be brewing tea for several minutes and care for the temperature, you can perform a flash brew to preheat the teapot and leaves, pour that out, and add hot water again for the real infusion. The flash infusion is not going to cost much in terms of lost flavor (or else you would not need a long infusion), and you can still sip on it so there is no loss, really.
I do this if the pot has cooled down completely and I know the following brew will be a "more than one minute" one.
faj
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Mon Jan 11, 2021 1:05 pm

Balthazar wrote:
Mon Jan 11, 2021 12:59 pm
I do this if the pot has cooled down completely and I know the following brew will be a "more than one minute" one.
This seems like a reasonable rule of thumb.
McScooter
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Mon Jan 11, 2021 3:34 pm

Youzi wrote:
Mon Jan 11, 2021 11:47 am

Based on my testing, unless you steep for really long times, over 6 minutes, heat retention doesn't really matter. Because it doesn't have enough time to take an effect, for 80% of a session, especially not at the beginning, which is the most important.
I agree with this. The differences in heat over a quick steep should be negligible for a majority of teas. And it's actually the volume of liquid relative to the surface area of the pot that is going to play a huge factor in the liquid's ability to retain heat. The water in larger teapots always stays warmer than in their smaller counterparts, all else being equal (which may seem counterintuitive). I can see heat loss being an issue with certain delicate Japanese greens, but not if teaware is properly warmed up prior, even if steeps are 45 seconds or greater.

This topic has always been super interesting to me, and it does of course have a "correct" answer because, it's science after all, but I don't know if anyone has ever published or investigated the thermal conductivity of various fired clays - zini, zhuni, hongni, etc. My understanding is that fired clay is a rather poor conductor of heat, and thus should help trap heat inside the pot. Aluminum and copper are hundreds of times better conductors of heat than porcelain, if I recall, and silver essentially trumps them all. Based on experience, porcelain gets hotter than fired clay.

As to thickness, think we need to find an engineer. How much more effective would a 2 inch tall copper heatsink be at pulling heat away from a microprocessor vs. 1 inch heatsink? I shoulda paid more attention in physics :lol:
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Iizuki
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Thu Jan 14, 2021 2:01 am

I think @McScooter arrived at the correct conclusion. A bigger pot is the way to go if you are looking for high/constant temperatures.

That's of course not always an option. In small pots, thin walls are probably going to be the best because of minimal clay/water ratio. Less heat lost in warming up the pot. Thick walls are probably better if preheated every steep, and even then the difference is probably very small. I'd vager that the clay material used is practically irrelevant.

Does any of this matter? I doubt I could identify the differences in the actual tea. In a blind test that is. So no, not really. I'm just going to keep buying pots that look nice.
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OCTO
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Thu Jan 14, 2021 3:54 am

I think one rarely discussed variable pertaining to heat retention is clay density and porosity..Once one have nose dived into the Yixing abyss long enough, you will find many ways to keeping a constant temperature using several methods. Then again, some smaller pots retain heat much better than others.... some thin walled, some thick walled, both are equally capable of retaining heat. Some pots are just so porous, heat loss is immediate even before the lid is placed on the pot. Some larger pots retains heat so well, it stays hot for a very very long time... some more than 10 minutes, some vice versa.... though the science says a thicker wall absorbs heat and thus causing heat loss.... preheat the walls and keep them hot... the result may surprise you!... hahahaha... big pot, medium pot, small pot... there's always a way to retain heat. The abyss darkens.... :twisted: :twisted: :twisted:

Cheers!!
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wave_code
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Thu Jan 14, 2021 4:41 am

I'm coming around on this pot size thing... most of my pots are around 100ml except for one 175. in the last year or so I've picked up around 4 pots that are 80ml, two of which still hold heat quite well and are great for certain teas, but not all. my 120ml nixing was originally irked me a bit because for some teas it was slightly more than I really wanted, though having learned where to fill to consistently to make it closer to 100ml/5g or just doing fewer/longer steeps has yielded nice results, particularly for leaves that expand more than I might anticipate and give things room to really full open up. the thing is, do those of you who use bigger pots feel there is a point where its diminishing returns or better to scale down? for example having a 200ml pot and only ever half filling it. do you find it starts to affect the liquor or aroma at some point negatively, or is it just whether it gets harder to judge volume? I would guess judging the amount of water used can also be easier/harder to practice depending on the shape.

I still actually don't have any purple clay pots and have been keeping an eye out on and off for ones I like for years now since I always heard it was the best choice for shu and liu bao. I'm happy to see recent quality modern pots from EoT and Mud and Leaves so I think its time to finally pick one up soon, but I'm wondering how it compares to nixing and if it might be redundant for me. Anyone with experience with both notice a big difference? Also are there any significant differences between Tian Qing Ni and DCQ?

I don't know if maybe I just know more now than when I first started, but it seems like in the last couple years its been getting much better for finding modern pots with more reliable sourcing and material quality control which is great. if I had vintage or antique pots I'm sure I wouldn't be mad at them, but for those of us who can't afford them or just don't want to take the gamble because of lack of knowledge its great to see other reliable options. same goes for things like reproduction cups I feel like I'm seeing more of, like EoT specifically working with an ex-forger to create something to their specification. I love the look of a lot of antique cups, but I'm always worried about things like lead leeching and toxic glazes, maybe overly so - but I'm happy to take a reproduction instead that I know is made to high spec and won't poison me.
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Balthazar
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Thu Jan 14, 2021 6:31 am

wave_code wrote:
Thu Jan 14, 2021 4:41 am
I still actually don't have any purple clay pots and have been keeping an eye out on and off for ones I like for years now since I always heard it was the best choice for shu and liu bao. I'm happy to see recent quality modern pots from EoT and Mud and Leaves so I think its time to finally pick one up soon, but I'm wondering how it compares to nixing and if it might be redundant for me. Anyone with experience with both notice a big difference? Also are there any significant differences between Tian Qing Ni and DCQ?
I picked up a DCQ pot (from the 90s "Malaysian private order" that EoT has some pots from) and a nixing pot last year, and have used both extensively since then. It is hard for me to pinpoint exactly why I prefer one over the other for any given tea. It seems to me that there is not only the question of which of the clays are more muting in general, but rather what notes each highlights.

It seems like I generally prefer the DCQ for liubao and nixing for shu puer (caveat: I'm not a big fan of shu, and my go-to pot for it would be a zini). For fuzhuan teas it's probably a draw; for heizhuans the DCQ comes out on top of the two (but would take second place to some of my hongni or zini pots).

Small sample size, differing pot sizes, and a dash of YMMV suggests all of the above should be regarded as fairly uncertain. But for the general question - is there a big difference between nixing and DQC - I'd say yes, I think the difference will be pretty clear to most drinkers out there.

(Slightly off topic, but I've been very surprised to see how well my nixing pot pairs with some hongcha and even roasted Taiwanese oolongs.)
wave_code wrote:
Thu Jan 14, 2021 4:41 am
I don't know if maybe I just know more now than when I first started, but it seems like in the last couple years its been getting much better for finding modern pots with more reliable sourcing and material quality control which is great. if I had vintage or antique pots I'm sure I wouldn't be mad at them, but for those of us who can't afford them or just don't want to take the gamble because of lack of knowledge its great to see other reliable options. same goes for things like reproduction cups I feel like I'm seeing more of, like EoT specifically working with an ex-forger to create something to their specification. I love the look of a lot of antique cups, but I'm always worried about things like lead leeching and toxic glazes, maybe overly so - but I'm happy to take a reproduction instead that I know is made to high spec and won't poison me.
Agreed. Although as far as the quality (and purity) of the material is concerned, you still have to take the vendor's claims at face value. But at least you're one step closer to the source (the pots were commissioned by the vendor himself), and provided that (1) the vendor is truthful and (2) the vendor hasn't been duped, you probably get what was advertised.

If I was in the market for a new yixing pot I wouldn't hesitate to pick up one of the new EoT offerings or the qingshuini pot from TWL.
Bac
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Thu Jan 14, 2021 5:17 pm

steanze wrote:
Fri Jan 01, 2021 12:57 pm
Bac wrote:
Thu Dec 31, 2020 4:38 pm

Any idea on this strange mengchen mark?
Pot is huge, half a liter probably.
Based on clay, workmanship, and seals, this teapot looks modern (post 1990s, probably also post 2000s). The seal is blurry so it's hard to see, but it does not look like it says "meng chen" to me.

I hope this helps. Happy New Year!
Sorry for the rotated images, but it wont let me post them if i try to correct them.
Is the pic, clearer?
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IMG_20210114_235237.jpg (309.83 KiB) Viewed 71 times
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Bok
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Thu Jan 14, 2021 6:29 pm

Bac wrote:
Thu Jan 14, 2021 5:17 pm
steanze wrote:
Fri Jan 01, 2021 12:57 pm
Bac wrote:
Thu Dec 31, 2020 4:38 pm

Any idea on this strange mengchen mark?
Pot is huge, half a liter probably.
Based on clay, workmanship, and seals, this teapot looks modern (post 1990s, probably also post 2000s). The seal is blurry so it's hard to see, but it does not look like it says "meng chen" to me.

I hope this helps. Happy New Year!
Sorry for the rotated images, but it wont let me post them if i try to correct them.
Is the pic, clearer?
ImageImage
It’s probably just a name of the artisan. Doesn’t really matter that much anyways...

What matters most is if it makes good tea!
Bac
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Fri Jan 15, 2021 6:20 am

It does indeed brew western style a very nice cup of shou pu. Incredibly muting.
Im still puzzled by the horizontal mengchen mark, it was using during the 90'?
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Bok
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Fri Jan 15, 2021 7:08 am

Bac wrote:
Fri Jan 15, 2021 6:20 am
It does indeed brew western style a very nice cup of shou pu. Incredibly muting.
Im still puzzled by the horizontal mengchen mark, it was using during the 90'?
Horizontal? The pic you posted is rotated 90 degrees... and it doesn’t say Mengchen either.

No idea about 90s chops.
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