Lao Zhuni from Yunnan Sourcing - A closer inspection

[Bert]

I own a shi piao style teapot bought from YS and the potter claims that it is made of zhuni clay from 92. This is even stamped on the bottom of the pot.
The shape is not bad crafted and it perfoms good. It is clear, that it can't be zhuni and I thought the clay was nonetheless ok. But for me something was wrong with this pot so I take a closer look at and in it. I know they are quite common and some of you might own a YS lao zhuni pot so I share my findings.

This is the surface of the pot, with a bit goodwill one can think of shrinkage lines:



What caused my attention was the underside of the handle. Is this a crack?



At the inside bottom of the pot I discovered this:



This looks suspicious...

A look at the spout confirmed my hypothesis:



Here you can see a border in the spout where the red surface changes to paler clay.


(This was my first opinion but it changed. Please read further down the thread.)

I think the pot was covered with a layer of more liquid clay and got brushed in order to make an appearance similar to shrinkage lines. This crack-like lines are the layer peeling of.

I am a bit disappointed. I mean come on - everybody knows this is not real zhuni! The pot could be more beautiful if the clay were not layered because the craftmanship is not that bad. Instead we got pots where the layer will flake off in time.. Poor pot

[betta]

Hi Bert, I've holded these pots and would like to confirm the same thing happened to me as well.
The pot is most likely painted using another clay which has different shrinkage rate than the clay beneath, so it cracks. Mine have a piece of metal planted in the clay inside the pot and can't get it out.

[hop_goblin]

First, I would like to preface my comments by stating that it is impossible to give more informed opinion without holding the pot.

Now that I got this out of the way. The pot is indeed not "Zhuni". Zhuni as I am sure Betta knows is extinct and uless you bought it from a master's studio or have acquired a pot that is 30 years of older, the chances are that it is not the real thing. Secondly, the term zhuni is used loosly today. Yes, in a sense it is Zhuni as zhuni just means crimson clay. However, it is not the famed Zhuni which is highly sought after due to its metallic and glossy appearance. Generally, Zhuni today refers to the sifting that the clay will go under. Before the clay is refined it will go thru a sifting process where the heavier impurities will fall to the bottom while the Zhuni layer will float to the top. This is the clay that zhuni is made of today. If you see shrinkage lines, this means that the clay had violent and drastic change for possibly two reasons. 1. the clay is Modern zhuni and there for went through some shrinkage as zhuni clay will do. 2. the potter did not control the kiln very well causing the stress fractures. As for the different color in the spout, sometimes you will see different colors on pots due to the different affects that temprature has on the clay in the kiln. Sometimes this is done on purpose where it is called YaoBian and other times it is due to inexperience on the potters part.

[betta]

Hop, thanks for sharing the info.

There's one thing I still doubt about processing of the zhuni clay. Clay consists of minerals of different density and I don't really think it's possible to purify a clay. Moreover iron is one of the most dense mineral (therefore wrought iron was used as material for old anchor despite its susceptibility to corrosion) so if the ore is crushed and washed with any liquid or water, most likely material consisting more iron will fall down the washing water rather than floating. I wonder that's the difference between old and new zhuni.
I've seen and holded an old zhuni pot in HK and it's neither 'clean' nor light like any of my own. The crawl mark is really fine and could be seen only if the pot is subjected to light from different angle, it's different than my pots, lobes lines are present, and the clay is dark red. It was said from original ore.
Lately I acquired one of such a pot and it really has the same characteristics like the pot I saw in HK.

[Salsero]

Hop, you never fail to floor me completely!

[bearsbearsbears]

What caused my attention was the underside of the handle. Is this a crack?

Yes. In a previous post on here I explained why cracks occur around handles, knobs, and lugs. Because they're thicker, they dry slower, and thinner parts that dry faster tend to pull away from them, causing cracks.

This looks suspicious...A look at the spout confirmed my hypothesis:

Here you can see a border in the spout where the red surface changes to paler clay.

I think the pot was covered with a layer of more liquid clay and got brushed in order to make an appearance similar to shrinkage lines. This crack-like lines are the layer peeling off.

I don't think that this pot was brushed in slip or had another application of clay, for a couple of reasons. Firstly, yixing is heavily burnished, as is evidenced by its shine and the relative smoothness in spite of its larger duan ni particles. Burnishing is usually done for hours: any second application of clay or slip would be rubbed off in the burnishing, but the LZN pots are the same clay appearance outside as in.

Secondly, I've chipped the lid on one of my pots, and the interior clay appears the same as the exterior clay. However, it's not a deep chip, so it's hard to say for certain.

I am a bit disappointed. I mean come on - everybody knows this is not real zhuni!

Do we? How much do we really know about "real" zhuni and who has taught it to us? I bring this up often on discussion of antique/zhuni pots, but Sothebys refuses to auction yixing pots because there is no expert who can identify antique yixing or "real" zhuni clay to any acceptible level.

There's no book on yixing clays that indicates how to identify it, and even if there were, what if two books said different things?

Most of the information on this comes from vendors. Accept their words with a grain of salt. Even truisms held online about zhuni and shrinkage lines aren't always true. Many things can be done to clay body or during firing to induce or prevent heavy shrinkage.

The pot could be more beautiful if the clay were not layered because the craftmanship is not that bad. Instead we got pots where the layer will flake off in time.. Poor pot

Layering the clay on yixing pots isn't an odd occurrence. Many yixing factory #1 pots were layered hong ni on top of zi ni, and vice versa. See this set of 1970s pots, for example: http://www.jingteashop.com/pd_yixing_dragon.cfm.

Furthermore, the nature of clay firing prevents layered clays from flaking off. When a clay is fired, it vitrifies. There's no reason why silicates in one clay wouldn't fuse with the silicates of another. Also, expert knowledge of two clays' shrinkage behaviors would be needed to layer any two clays successfully without it distorting the pots shape in the firing. Two clays with roughly equal shrinkage rates will fuse relatively easily. Korean slip inlay pots from the 11th century and after exist today with none of the slip falling out. In the case that this pot is layered, I wouldn't worry too much about damage.

As far as the damage you already see, I think that's evidence of drying errors caused by uneven wetness, and consistent with what I've seen on other yixing pots and stoneware pots I've seen dry unevenly since taking ceramics courses here in LA.

Last note: nothing in here should imply that I'm at all sure of the zhuni nature of the clay. I just want to point out that a lot of your reasoning is flawed, and you have less reason to despair.

[hop_goblin]

Hop, thanks for sharing the info.

There's one thing I still doubt about processing of the zhuni clay. Clay consists of minerals of different density and I don't really think it's possible to purify a clay. Moreover iron is one of the most dense mineral (therefore wrought iron was used as material for old anchor despite its susceptibility to corrosion) so if the ore is crushed and washed with any liquid or water, most likely material consisting more iron will fall down the washing water rather than floating. I wonder that's the difference between old and new zhuni.
I've seen and holded an old zhuni pot in HK and it's neither 'clean' nor light like any of my own. The crawl mark is really fine and could be seen only if the pot is subjected to light from different angle, it's different than my pots, lobes lines are present, and the clay is dark red. It was said from original ore.
Lately I acquired one of such a pot and it really has the same characteristics like the pot I saw in HK.

Good observation Betta. When I mean float to the top, I didn't mean the actual top layer. What I meant is that the impurities which are far more heavier than the clay slurry itself. Yes, iron is dense but when we are dealing with parts per million they are undoubtably small enough to have some buoyancy. What separates Modern Zhuni from Older extinct zhuni is the size of the particles during processing. New or Modern Zhuni can not get as "small" for the lack of a better word as older zhuni. Secondly, Old zhuni was mined in the Yellow Dragon Hill mine which currently has very little activity due to its depletion. While modern Zhuni is mined in newer locals. Again, as for differnces in color, remember, Zhuni clay is almost badge before it is fire. Only after firing does it turn into the lovely crimson color that we see.

[Bert]

Nice information about the zhuni - thanks!


@bearsbearsbears: Hm.. quite good arguments. But what does not fit is this:



On the left this looks like flaking off to me, notice that the Duanni particels are covered with red clay.


But I got a new hypothesis. If you look at the surface you will notice that the duanni particels are quite bumpy. But where the lid sits on the body the surface is pretty even. Maybe the pot was brushed with water in order to bring the duanni particels out which seem to be less solutable then the red clay. This would explain the border in the spout. Maybe the inside was brushed too but wasn't burnished like the outside of the pot, remaining a more liquid layer of washed off red clay at the inside bottom.
If the pot were just burnished I think the surface would be more even.


Now I don't think the outside will flake off, but at the inside I still think this can happen. Personally a even surface would have been more appealing to me.

Please don't get me wrong. I use the pot, like it and it performs good. I like Yunnan Sourcing too and am glad for their offerings.

[Bert]

I am a bit disappointed. I mean come on - everybody knows this is not real zhuni!

Do we? How much do we really know about "real" zhuni and who has taught it to us?

I can't judge real zhuni. But if the clay is such precious a pot for 30$ won't be zhuni. Or does the fabrication of modern zhuni allow such prices?

The pot could be more beautiful if the clay were not layered because the craftmanship is not that bad. Instead we got pots where the layer will flake off in time.. Poor pot

Layering the clay on yixing pots isn't an odd occurrence. Many yixing factory #1 pots were layered hong ni on top of zi ni, and vice versa. See this set of 1970s pots, for example: http://www.jingteashop.com/pd_yixing_dragon.cfm.

Furthermore, the nature of clay firing prevents layered clays from flaking off. When a clay is fired, it vitrifies. There's no reason why silicates in one clay wouldn't fuse with the silicates of another.

I know that this method is common. But on the net (don't know the url anymore) I saw pictures of pots where the layer started flaking off, mostly at the side of the lid. Maybe this primed my imagination with fear...

[MarshalN]

Two things:

Those bigger particles are not duanni, but something else. What exactly (in this case) I do not know. On older pots they are simply the same material as zhuni's original stone, but not grounded down, afaik.

As for your argument that burnishing would remove all traces of the slip dip -- BBB, I'd like to remind you of the "outside red, inside purple" pots which were dipped into a red clay slip. They are quite shiny and the red clay slip was obviously not burnished off as a result.

Having said those two things, I'd have to say that my humble opinion is that these are not zhuni pots. I don't know what they are, but I don't think they're zhuni for the simple reasons of colour and feel. I think they are made with something else, or more likely, of "modern" zhuni which are not the same thing as "traditional" zhuni and mined from different areas, as far as I am aware.

[chrl42]

To Hop Goblin and Betta.

You guys' statements are just too damn long I can't cut it through..

And I would like to add more of my opinion to it.

First, refinement. Was developed when Yixing teapots scored in huge popularity in Taiwan, in 90's. Because the Taiwanese believed one way to distinguish its quality was purity, but yixing clay is originaly of mixed particles(iron, manganese, qualtz) how could it be? so as Hop Goblin pointed out it's done with water. Don't know any far this is just what I heard.

Second, color or shrinkage of Lao Zhuni.
Redness can be defined by iron content and shrinkage is defined by alumina content. And degree of redness, as much as the Chinese favored for, go by
Huang Long Shan > Zhao Zhuang > Shao Mei Yao > Hu Fu(modern zhuni).

And that's how Zhuni was mined in order. First it was from Huang Long Shan(yellow dragon mt) then went scarce so they found out other mountain called Zhao Zhuang and that was when Zhuni's demend arose to peak so went scarce eventually. Then near Huang Lung mt they found out Shao Mei Yao, famous wrinkled Zhuni. 3 of mountains already have been forbidden by goverment of mining in 80's. The only one still being mined is Hu Fu, new Zhuni.

Also temperature of heating, intentional addition of iron red powder could affect in redness.


Shao Mei Yao has most wrinkles, cos it lacks alumina that holds from shrinking. And that's why it's notorious for cracking in a kiln that leads to only 30 percent of success. That's why many famous masters don't wanna make with Zhuni because of its low percentage and even if it comes alive from heating, the looking is far from perfection.
Huang Lung and Hu Fu Zhuni tends to have less wrinkles.


Any different idea welcomed

[betta]

Secondly, I've chipped the lid on one of my pots, and the interior clay appears the same as the exterior clay. However, it's not a deep chip, so it's hard to say for certain.

Do we? How much do we really know about "real" zhuni and who has taught it to us? I bring this up often on discussion of antique/zhuni pots, but Sothebys refuses to auction yixing pots because there is no expert who can identify antique yixing or "real" zhuni clay to any acceptible level.

There's no book on yixing clays that indicates how to identify it, and even if there were, what if two books said different things?

I wouldn't be happy if the colour of the crack of 'so called zhuni pot' has similar colour as in or out of the pot.
I wonder why don't Sotheby test the clay in the lab like what they do with jadeite?

Because of so many forgeries, it's very difficult to differentiate real from fake zhuni, therefore the best way or learning is to hold as many pots as possible (which would also means to pay more for 'tuition pot') and to an extreme condition by breaking it, so no formal education by doing this.

Anyway, who would like to share their experiences obtained from their big loss of money? The reward for identification is way too less than involving in the business, right?

PS: Hop and Chrl, thanks for sharing the info

[chrl42]

but the LZN pots are the same clay appearance outside as in.

Secondly, I've chipped the lid on one of my pots, and the interior clay appears the same as the exterior clay. However, it's not a deep chip, so it's hard to say for certain.

[
Do we? How much do we really know about "real" zhuni and who has taught it to us? I bring this up often on discussion of antique/zhuni pots, but Sothebys refuses to auction yixing pots because there is no expert who can identify antique yixing or "real" zhuni clay to any acceptible level.

There's no book on yixing clays that indicates how to identify it, and even if there were, what if two books said different things?

Layering the clay on yixing pots isn't an odd occurrence. Many yixing factory #1 pots were layered hong ni on top of zi ni, and vice versa. See this set of 1970s pots, for example: http://www.jingteashop.com/pd_yixing_dragon.cfm.

Furthermore, the nature of clay firing prevents layered clays from flaking off. When a clay is fired, it vitrifies. There's no reason why silicates in one clay wouldn't fuse with the silicates of another. Also, expert knowledge of two clays' shrinkage behaviors would be needed to layer any two clays successfully without it distorting the pots shape in the firing. Two clays with roughly equal shrinkage rates will fuse relatively easily. Korean slip inlay pots from the 11th century and after exist today with none of the slip falling out. In the case that this pot is layered, I wouldn't worry too much about damage.

Jeez, this is long.
But I want to talk different thing from what I think was a mistake.

First, in and out of Zhuni clay.
I don't know how many Zhuni clays you have been breaking but it's common knowledge broken inside shows darker color than outside due to lake of oxygen.
Same thing happens other reddish yixing clay such as Qing Shui ni, Di Cao Qing or Hong ni.

Second, lack of knowledge of Soderby. So Soderby is representing of capitalistic western world. But you have to realize Yixing teapot is from red China where goverment don't want to connect outside. Qing emperor's stamp(stolen by the french) was auctioned in Soderby(or was it christie?) and guess what the Chinese goverment might have felt at that time?
It's not there is no book identifying Yixing clay but is there is no such book in English. chashu.cn is Chinese website on tea and you can find there are 55 books on yixing teapot. What about universities and labs inspecting content of a clay? I've been living in Korea, China and USA. And information about yixing in America was uncomparably small than I could find in Korea and China.

Third, coating of a clay. What's misleading is yixing factory didn't use that Hua Zhuang method for quality-related reason. Reason is it was done to fit the size of a pot(since every clay has different rate of shrinkage) and to save time in making. Jingteashop advertised as it's some kind of rare method for good but for example you will find hongni-dipped zini but you won't find zini-dipped hongni. It was strictly communist philosophy under cultural revolution.


Sorry, I raised my voice a bit cos air pollution in Beijing is so bad

[Salsero]

Sorry, I raised my voice a bit cos air pollution in Beijing is so bad

I thought they were taking drastic measures to improve the air quality for the Olympics?

Interesting comments about the history of Sotheby's, Christie’s selling Chinese treasures.

[betta]

Sorry, I raised my voice a bit cos air pollution in Beijing is so bad

Chrl, it's fine, I corrected my comment based on your information.