Clay properties of different periods

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steanze
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Fri Mar 16, 2018 12:29 pm

Shine Magical wrote:
Fri Mar 16, 2018 11:51 am
I’ve been using a duan ni for shou for a while, and it has gotten quite dark since then. It’s a medium brown now. I almost never poured tea over the pot.

I want to reset it to use it for young sheng. If I boil the pot to reset it, will most of the brown color go away? I feel like it’s there to stay given how staining shou can be.

Maybe it will also taint the flavor of sheng.
Put a bit of baking soda in the pot, a teaspoon of water, and use a paper towel to scrub the inside with the baking soda+water paste :)
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tealifehk
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Fri Mar 16, 2018 1:38 pm

Bok wrote:
Fri Mar 16, 2018 8:39 am
tealifehk wrote:
Fri Mar 16, 2018 8:30 am
I think it's heat retention, wall thickness and porosity. Duanni is known to be porous. I have pots in the same 80s zini clay and the thicker one mutes much more than the thinner ones! Similar firing level and all.
I agree and have noticed the same thing over the whole range of my teapots, from various Yixing to Wood fired Taiwanese pots, outside only glazed and even porcelain:

Wall thickness is what seems to influence more than the other factors - After seasoning and raising the pot.
My best pots are the thinnest, no matter the material.
I like some muting for dank pu and the roastiest oolongs!
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Brent D
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Fri Mar 16, 2018 3:22 pm

So what are the more desirable years for f1 Zini? Would a green label Nei Zi Wai Hong have generally superior characteristics to a white label Zini?
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steanze
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Fri Mar 16, 2018 5:11 pm

Brent D wrote:
Fri Mar 16, 2018 3:22 pm
So what are the more desirable years for f1 Zini? Would a green label Nei Zi Wai Hong have generally superior characteristics to a white label Zini?
These are both on the low end of F1 zinis. 70s qsn is decidedly better than both. But the best zinis in F1 are jia zini and ben zini of the 60s, too bad a pot of those can cost over $1000 when you source directly from Asia... western facing sellers never offer those.

... then, there's ROC and late Qing :)
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Demea
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Fri Mar 16, 2018 5:24 pm

steanze wrote:
Fri Mar 16, 2018 5:11 pm
70s qsn is decidedly better than both.
You mean something like this?

http://2088taiwan.com//index.php?route= ... duct_id=73
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steanze
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Fri Mar 16, 2018 8:00 pm

Demea wrote:
Fri Mar 16, 2018 5:24 pm
You mean something like this?

http://2088taiwan.com//index.php?route= ... duct_id=73
yes like that
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Brent D
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Sat Mar 17, 2018 5:08 pm

From reading all this here, it seems like there is no reason to buy any pot made after 1977
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steanze
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Sat Mar 17, 2018 5:15 pm

Brent D wrote:
Sat Mar 17, 2018 5:08 pm
From reading all this here, it seems like there is no reason to buy any pot made after 1977
No, the F1 zini pots after 1977 are good, much better than modern pots and often reasonable for the price. However I'd pick a heixingtu or some other zini rather than the neizi or the 1990s ones. The green label early 80s or the square label ones are often pretty good.

Hongni instead is much better before 1977, but also much more expensive. So in that case it depends on your budget. But yes, if you can get one, a pre-1977 is totally different from post in terms of hongni.
Chadrinkincat
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Sat Mar 17, 2018 5:35 pm

Brent D wrote:
Sat Mar 17, 2018 5:08 pm
From reading all this here, it seems like there is no reason to buy any pot made after 1977
There are plenty of decent pots made during green label and even Fang yuan pai periods. They're less collectible than pre-77 pots but still good for tea making. Also it's a good idea to have a couple cheaper pots for daily casual drinking so you don't have to risk breaking a $500 pot every morning.
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tingjunkie
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Thu Jun 14, 2018 5:40 am

Personally, I don't subscribe to a rule about older clay always being better, but there are some considerations people have not mentioned yet. I may have my time periods or years off, so please correct me if I'm mistaken:

1) Clay Processing: Prior to ROC period most clay was crushed and processed by hand. The Yixing ores were crushed by hand, or in a grinding mill powered by livestock. This contributed to a certain level of clay particle size and porosity. After ROC, it was more common for the ore to be crushed by machine, and lead to a different level of porosity. I also believe that once clay blocks were made from the ore, in the past they were aged for longer than in Factory times. Generally speaking, the longer a clay is aged or "fermented" the better for the teapot. The Factories were trying to crank out lots of Yixing wares, and aging the clay for decades was not in their plan. Finally, when clay is worked entirely by hand, and teapots are entirely hand built by beating slabs of clay in to shape, you're going to end up with a different porosity level than when pots are half hand made or completely mold made. People talk about how beating the clay by hand creates a smooth outer "skin" to the clay, and achieves a double layer, each with its own porosity.

2) Firing: Prior to the 1960's, wood-fired dragon kilns were the typical way to fire Yixing pots. After 1960's the Factories switched to using coal and gas powered down-draft and tunnel kilns instead. Later on past F1 days, even electric kilns were used more frequently, changing the characteristics of the teapots yet again. Of course these very different kilns will have different effects on how the teapots come out and perform.

3) Clay Masters: Back in the old days, Yixing had master potters, master calligraphers, AND clay masters. The latter were folks who only processed clay, and were often not potters themselves. I get the impression that a lot of their specialized knowledge has been lost over the years.

I'm not trying to imply fully hand made pots will always outperform half-hand made pots, or that dragon kiln pots are always superior to downdraft kiln pots, but there's definitely something to be said for Yixing's magical reputation being formed well before the advent of the modern processes invented in the later half of the 20th Century. I think there's also something to be said for people who are passionate about anything to romanticize the past and declare that things just aren't like they used to be, whether that's true or not.
Last edited by tingjunkie on Thu Jun 14, 2018 12:56 pm, edited 1 time in total.
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Bok
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Thu Jun 14, 2018 8:00 am

tingjunkie wrote:
Thu Jun 14, 2018 5:40 am
Personally, I don't subscribe to a rule about older clay always being better, but there are some considerations people have not mentioned yet. I may have my time periods or years off, so please correct me if I'm mistaken:

1) Clay Processing: Prior to ROC period most clay was crushed and processed by hand. The Yixing ores were crushed by hand, or in a grinding mill powered by livestock. This contributed to a certain level of clay particle size and porosity. After ROC, it was more common for the ore to be crushed by machine, and lead to a different level of porosity. I also believe that once clay blocks were made from the ore, in the past they were aged for longer than in Factory times. Generally speaking, the longer a clay is aged or "fermented" the better for the teapot. The Factories were trying to crank out lots of Yixing wares, and aging the clay for decades was not in their plan. Finally, when clay is worked entirely by hand, and teapots are entirely hand built by beating slabs of clay in to shape, you're going to end up with a different porosity level than when pots are half hand made or completely mold made. People talk about how beating the clay by hand creates a smooth outer "skin" to the clay, and achieves a double layer, each with its own porosity.

2) Firing: Prior to the 1960's, wood-fired dragon kilns were the typical way to fire Yixing pots. After 1960's the Factories switched to using gas powered down-draft and tunnel kilns instead. Later on past F1 days, even electric kilns were used more frequently, changing the characteristics of the teapots yet again. Of course these very different kilns will have different effects on how the teapots come out and perform.

3) Clay Masters: Back in the old days, Yixing had master potters, master calligraphers, AND clay masters. The latter were folks who only processed clay, and were often not potters themselves. I get the impression that a lot of their specialized knowledge has been lost over the years.

I'm not trying to imply fully hand made pots will always outperform half-hand made pots, or that dragon kiln pots are always superior to downdraft kiln pots, but there's definitely something to be said for Yixing's magical reputation being formed well before the advent of the modern processes invented in the later half of the 20th Century. I think there's also something to be said for people who are passionate about anything to romanticize the past and declare that things just aren't like they used to be, whether that's true or not.
Nice summary and post, thanks! I second your last paragraph, putting in words what I had been thinking as well for some time.
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ShuShu
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Thu Jun 14, 2018 6:58 pm

tingjunkie wrote:
Thu Jun 14, 2018 5:40 am


L

2) Firing: Prior to the 1960's, wood-fired dragon kilns were the typical way to fire Yixing pots. After 1960's the Factories switched to using coal and gas powered down-draft and tunnel kilns instead. Later on past F1 days, even electric kilns were used more frequently, changing the characteristics of the teapots yet again. Of course these very different kilns will have different effects on how the teapots come out and perform.
Thanks for the post!
I’m curious about this point. How would type kiln effect or change the performance of the pot? (Too bad this is an experiment I can’t really do as I don’t have pots that only differ in the kiln in which they were fired
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tingjunkie
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Thu Jun 14, 2018 8:58 pm

ShuShu wrote:
Thu Jun 14, 2018 6:58 pm
How would type kiln effect or change the performance of the pot? (Too bad this is an experiment I can’t really do as I don’t have pots that only differ in the kiln in which they were fired
I don't have the pottery knowledge to give you a truly academic answer, but the two big things I can think of are temperature control inside the kiln, and duration of the firing. Wood fired dragon kilns were impossible to have even temperatures all throughout, so there were often hotter areas and cooler areas. The kiln operators knew this and would try to adapt accordingly, but it would still result in pots being fired at different levels, even on the same firing. This is how we have some pots that are called "yao bian" where they fire at a high enough temperatures to get scorch marks, and the clay becomes crystallized and loses porosity. Even in down draft and tunnel kilns it could still happen that pots were over or under fired, but it was more consistent. Dragon kilns also took a lot longer to fire pieces- sometimes several days, depending on conditions. I'm not sure exactly how that would cause a difference in the final teapot, but I'm sure it did.
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tingjunkie
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Thu Jun 14, 2018 9:06 pm

Billy Moods' article here is a classic source of information on Yixing for the English speaking world. The entire thing is worth reading, but in particular the two sections "THE ZISHA PARTICLES" and "PROCESSING OF ZISHA CLAY" really speak to the discussion in this thread.
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steanze
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Thu Jun 14, 2018 9:57 pm

tingjunkie wrote:
Thu Jun 14, 2018 8:58 pm

I don't have the pottery knowledge to give you a truly academic answer, but the two big things I can think of are temperature control inside the kiln, and duration of the firing. Wood fired dragon kilns were impossible to have even temperatures all throughout, so there were often hotter areas and cooler areas. The kiln operators knew this and would try to adapt accordingly, but it would still result in pots being fired at different levels, even on the same firing. This is how we have some pots that are called "yao bian" where they fire at a high enough temperatures to get scorch marks, and the clay becomes crystallized and loses porosity. Even in down draft and tunnel kilns it could still happen that pots were over or under fired, but it was more consistent. Dragon kilns also took a lot longer to fire pieces- sometimes several days, depending on conditions. I'm not sure exactly how that would cause a difference in the final teapot, but I'm sure it did.
+1, temperature in dragon kilns was uneven. You can find more under-fired or over-fired pots during Qing. And sometimes even firing differences on the same pot, like this:


By and large: higher fired -> less porous, lower fired -> more porous.
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