Questions on Zhuni

[Tead Off]

Most of the yixing pots are now fired in gas kiln. Normally fired twice.

Why do you say, 'normally fired twice'? Please quote a reliable source.

Because it is tremendously hard to make a single fired yixing teapot that looks neat. You fired once, then you make the correction on the lid fit, etc. and then fire the second time to even out the colour.

Firing only once means you can't make any fine detail correction.

Most of my pots are fired twice and only some handmade ones that follow the very traditional way fire just once and doesn't even use the hand wheel to help forming the pot.

I might get a wrong impression, but the vast majority of the yixing pots I encountered are fired twice. I don't really know about the mass product chemical added yixing.

Bank,
I think you are only talking about modern pots, after factory production ended. Because most of my pots are 90's and earlier, I don't think secondary firing was done. So, when you say the vast amount of pots you've seen are twice fired, I think you are referring to newer production. Maybe my head is stuck in older pots because I trust the clays more than the newer production.

For glazed wares, twice firing is the norm.

[William]

Bank,
I think you are only talking about modern pots, after factory production ended. Because most of my pots are 90's and earlier, I don't think secondary firing was done. So, when you say the vast amount of pots you've seen are twice fired, I think you are referring to newer production. Maybe my head is stuck in older pots because I trust the clays more than the newer production.

I am honestly not so sure that even modern teapots are usually fired twice.
For example, if we take EoT's handmade teapots, only a tiny amount of them are fired twice, which are also much more expansive than the ones fired only one time .. so, if we are talking of modern teapots that costs 200 USD or less, than I am extremely dubious.

[Tead Off]

Bank,
I think you are only talking about modern pots, after factory production ended. Because most of my pots are 90's and earlier, I don't think secondary firing was done. So, when you say the vast amount of pots you've seen are twice fired, I think you are referring to newer production. Maybe my head is stuck in older pots because I trust the clays more than the newer production.

I am honestly not so sure that even modern teapots are usually fired twice.
For example, if we take EoT's handmade teapots, only a tiny amount of them are fired twice, which are also much more expansive than the ones fired only one time .. so, if we are talking of modern teapots that costs 200 USD or less, than I am extremely dubious.

According to the links Kyarazen quoted, which I looked at, it seems the newer production technique of twice firing is becoming common. There are probably some who don't fire twice. As was stated, it's mainly because of the difference in modern clay. Those links in Chinese are extremely difficult to understand because of the poor translation available with the browsers. In any case, I remain more or less disinterested in newer Yixing.

[bankung]

Bank,
I think you are only talking about modern pots, after factory production ended. Because most of my pots are 90's and earlier, I don't think secondary firing was done. So, when you say the vast amount of pots you've seen are twice fired, I think you are referring to newer production. Maybe my head is stuck in older pots because I trust the clays more than the newer production.

I am honestly not so sure that even modern teapots are usually fired twice.
For example, if we take EoT's handmade teapots, only a tiny amount of them are fired twice, which are also much more expansive than the ones fired only one time .. so, if we are talking of modern teapots that costs 200 USD or less, than I am extremely dubious.

According to the links Kyarazen quoted, which I looked at, it seems the newer production technique of twice firing is becoming common. There are probably some who don't fire twice. As was stated, it's mainly because of the difference in modern clay. Those links in Chinese are extremely difficult to understand because of the poor translation available with the browsers. In any case, I remain more or less disinterested in newer Yixing.

Thats why the factories pots are quite rare to have good, let alone perfect, lid fit.

For EoT handmade pots, I have one thats fairly priced (~GBP150?) and I'm quite sure that its fired twice even though not stated on the website. I wonder if the other pots made by the same potter in the similar style are gonna be different. In facts, firing twice is not that costly. The most costly thing that could happen is that the pot couldn't be sold as the lit doesn't fit well.

Also, the number of firing don't imply the shininess or the level of porosity. It depends on the sieve size used when preparing the clay and the smoothing procedure at the end.

[bankung]

Lastly, I don't really think the high quality contemporary pots are inferior to the factory mass production in the 90s, even in the term of clay.

If you have an unused factory pot, try pouring the hot water in, smell the pot and compare it to the GOOD modern one, I bet you will find the modern one has less off smelling. For some very good modern pots, I don't even have to boil or clean the interior before the first usage.

[AT333]

I am curious about the term plasticity of zhuni in raw form before they are form into pot for firing. How do we define the plasticity in zhuni? Is zhuni at that stage a slurry paste or a dry paste like other clay that can be formed by wooden mallet? I always have the impression that is is too soft like a wet slurry to be effectively fit into any mold or form by wooden mallet.

Secondly, I am also curious if they can be recycled. Can the shard be ground into fine powder and go through the same process of processing and making another teapot? Can that be done by other clay too?

Your explanation on shrinkage on different era makes a lot of sense. There are significant textural difference between different era. Perhaps the pace they fired the pot makes a lot of difference. Now I began to wonder if the pace and duration of firing affect the color and texture of the pot, rather than solely depending on temperature as many would think. What is your thoughts on this?

I also wonder how they make those little super thin walled light weight zhuni pots in the early era. It seems so impossible to make it so thin and perfect being such a soft clay. Do they use mold? When do they start using mold?

I am still curious about the above and wonder if anyone has any idea. Thanks.

[AT333]

Bump

[kyarazen]

i would think plasticity largely refers to how "elastic" the clay is, able to take on shapes without crumbling or breaking.

in principle zhuni pots are always made like other hongni/zisha pots, i.e. in a dry paste style. but due to absolutely pure non-plasticity it might just simply feel like making sand castles and hope that they stay together. if it were really plastic, real zhuni pots could have been wheel thrown, like how in dehua and jing dezhen some vessels can be made really thin, but there is no evidence on the possibility of zhuni being done this way

pace and duration probably is something worth exploring again, repeated oxidation/reduction would give neutral vessels rather than one way oxidation or one way reduction modern vessels.

how the super thin zhuni pots of qing to ROC were made is not quite clear. KS lo in the stonewares of yixing did mention that moulds were used already in the ming dynasty. maybe some day when i'm interested in zhuni i might explore the subject more deeply. there are works of xi-sheng, wang yin chun, etc in the late qing to ROC era that are made of zhuni, super thin and very delicate.. everyone attributes it to the mastery of these makers, but whether there was a secret technique.. it can be explored if one contacts the right sources/people. some of these pieces have perfect shapes, no warp! !!

I am curious about the term plasticity of zhuni in raw form before they are form into pot for firing. How do we define the plasticity in zhuni? Is zhuni at that stage a slurry paste or a dry paste like other clay that can be formed by wooden mallet? I always have the impression that is is too soft like a wet slurry to be effectively fit into any mold or form by wooden mallet.

Secondly, I am also curious if they can be recycled. Can the shard be ground into fine powder and go through the same process of processing and making another teapot? Can that be done by other clay too?

Your explanation on shrinkage on different era makes a lot of sense. There are significant textural difference between different era. Perhaps the pace they fired the pot makes a lot of difference. Now I began to wonder if the pace and duration of firing affect the color and texture of the pot, rather than solely depending on temperature as many would think. What is your thoughts on this?

I also wonder how they make those little super thin walled light weight zhuni pots in the early era. It seems so impossible to make it so thin and perfect being such a soft clay. Do they use mold? When do they start using mold?

[chrl42]

Well..Zhuni may not be able to be thrown on wheels, but so is Duanni, Zini etc..matter of fact, Zhuni not plastic is quite a new word to me..not seen from text books or Zhu Ze-wei's that clay book.

Usually, sand type Yixing clays are called unplastic like Di Cao Qing, Duan Ni, Lv Ni etc so Pin Pei (mixing clay) or storing (aged clay gets more plastic) is often done to these clays to enhance plasticity. Think about Nian Gao Tu, which was made to play in slipcasts, was the most Zhuni-like Factory-1 clay with fine particles and smooth.

Zhuni was often made very little and thin without mixing, none-plastic clays can't be made this way..but I'm no potter..

[AT333]

Thanks chrl42 and kyarazen. I am very intrigue with this clay. Not many concrete literature is found and yet in the early era, many pots could be done in this clay in super impossible light, perfect fit, super thin and some really very small. In that era with little technology and yet so perfect.

[kyarazen]

kaolin and other additives are added to zisha to enhance plasticity nowadays that they can be wheel spun easily. through blending between zisha clays, i'm not sure if plasticity would be enhanced.

was niangaotu ever slip-casted? i've yet to see an example but would love to. there are many theories on what niangao is. attached is one of the more credible explanations of this material

早期壺入門之五：關於「年糕土」。
「年糕土」是一廠在「綠標」時期出現的一種特有土胎，其色澤介於紅土與紫砂中間，未泡養前初看不起眼，泡養後會呈現一種特殊色澤的細緻感，很像台灣人早期愛吃的甜年糕，故稱之「年糕土」。
關於「年糕土」出現的原因，坊間有多種説法，如「剩土拼配説」等，但其實一廠的用土並非一廠自己調配生產，而是由「宜興礦業公司」所供應。故個人認為其實年糕土就是當時挖到的某一層礦層而己，只是後來沒有再挖到類似的礦土而已。
「年糕土」的特性，基本上也是介於紅土及紫砂之間，收縮比和紫砂比較接近，泡茶效果也是介於二者之間，不必過度神化。
最後關於年糕土的判斷，在器型上一定是綠標期，故必須符合綠標器型的標準。在色澤上，它也是介於紅土及紫砂中間，不紅不紫(照片看起來偏紅了點，實品沒那麼紅)。照片中是紅土丶年糕土及淸水泥的比較（有貼綠標的是年糕土），請大家參考。

in principle, the clay blend that was milled for slip-casting between '58 and 60 was the finest particle size clay ever in F1, even finer than nian-gao. but neither niangao nor this 58-60 hong ni ever fired up to zhuni texture......

zhuni appears to remain as a percentage component than an absolute component. these are the various groups/grades that appear to exist

1) creamy jade like textures : players of ming to qing tomb excavated/robbed zhuni only, mostly small items. strangely, many of these pots have excellent fits, shape, and little warp. this led a belief in a size limitation of zhuni. many of these pots are very delicate and thin walled, clay is very smooth and appears less blended

2) thai zhuni with brass handles, these zhuni takes on an orangey to red hues, seldom burgundy. texture is less jade like, still v smooth but the pots are huge, 500ml and even more. walls are thicker

3) pear skin, apparently blended with post fired ground particles

4) wet tomb excavated, the zhuni's firing has receded and pot appears orangey/very porous

5) modern electrokilned zhuni, thick walls, glossy and occassionally creamy

6) taiwan driven zhuni replicas

Well..Zhuni may not be able to be thrown on wheels, but so is Duanni, Zini etc..matter of fact, Zhuni not plastic is quite a new word to me..not seen from text books or Zhu Ze-wei's that clay book.

Usually, sand type Yixing clays are called unplastic like Di Cao Qing, Duan Ni, Lv Ni etc so Pin Pei (mixing clay) or storing (aged clay gets more plastic) is often done to these clays to enhance plasticity. Think about Nian Gao Tu, which was made to play in slipcasts, was the most Zhuni-like Factory-1 clay with fine particles and smooth.

Zhuni was often made very little and thin without mixing, none-plastic clays can't be made this way..but I'm no potter..

[AT333]

Is there any images and documentation on the process of slip casting and handmade zhuni? How do we identify slip cast and fully handmade zhuni teapot? Is it more apparent in slip cast or in handmade zhuni teapot for those lateral shrinkage lines between the base and body?

[chrl42]

Is there any images and documentation on the process of slip casting and handmade zhuni? How do we identify slip cast and fully handmade zhuni teapot? Is it more apparent in slip cast or in handmade zhuni teapot for those lateral shrinkage lines between the base and body?

What I meant was Factory-1 wanted to invent clay that is available for slipcasting, but from what I know, they failed Nian Gao Tu was left-over clay for that purpose.


Slipcasting, from what I know, is low-end way of making Yixing teapot...cheaper than wheel-thrown Yixings..they have to add many none-Yixing clays to do that...but during the CR period...quantity was a major issue over quality..so they had to design numerous moulds, operate a giant heavy-oil kiln, sought for slipcasting ways, add chemical powders for coloring etc...

But Factory-1 still was the only government factory where all the legendary Yixing potters were in..so they were avaiable to continue the 'secret' of Yixing pottery that was passed on since Ming-Qing eras..

[kyarazen]

with regards to niangao being a left over from the slipcasting experiment that is what many mainland blogs/website and articles i.e. on tieba.baidu seem to postulate but that might not be the actual account.

F1 gave up slip casting in 1960 way before the CR started. Niangao was also not at the right consistency for slipcasting if you do a side by side comparison with '58-60 F1 slip cast hongni, vs Niangao, vs modern slip cast.

niangao only appeared during the green label period ('77 to 82), during that period of time, F1 was supplied by Yixing Kuang Ye Company. if it was a blend, why are people unable to replicate it today? i would love some modern cheap niangaos , i mean who wouldnt.. since its so nice to raise it, glossy in a few uses sometimes.

What I meant was Factory-1 wanted to invent clay that is available for slipcasting, but from what I know, they failed Nian Gao Tu was left-over clay for that purpose.


Slipcasting, from what I know, is low-end way of making Yixing teapot...cheaper than wheel-thrown Yixings..they have to add many none-Yixing clays to do that...but during the CR period...quantity was a major issue over quality..so they had to design numerous moulds, operate a giant heavy-oil kiln, sought for slipcasting ways, add chemical powders for coloring etc...

But Factory-1 still was the only government factory where all the legendary Yixing potters were in..so they were avaiable to continue the 'secret' of Yixing pottery that was passed on since Ming-Qing eras..

[kyarazen]

in my course of investigation back then, here are some of the things that i had seen, especially on the taiwanese forums :


person 1 says :

年糕土：源于台湾玩壶人的称呼，最初出现在上世纪约在60年代末~70年代，当时 ​​紫砂一厂尝试操作“灌浆成型”
的方式，提高产量。将某一矿山的红泥经过相当的磨炼使之颗粒更加细腻(约100目)以增加其流动性，
但是由于浆性太高，无法用传统的拍打或挡坏的方式成型。其主要原因是：因为紫砂的颗粒是几何型有菱有角的
结构，其流动性较差不适合注浆方式乃至是手拉坯成型的方式，结果尝试失败。当时为注浆所练制的泥料厂，
为了不浪费再利用资源，就再调配一些紫砂泥以恢复其硬度，这就是年糕土的由来。是不是和“冲浆料”
的方式方法很接近呢？
特点：1、调配方法：红泥（100目或以上） +紫砂泥。。。。。。
2、泥色：红褐偏咖啡色，并且整批泥料色泽不甚一致。 以上取自宜兴紫砂爱好者联盟。

which roughly means in end 60s, to early 70s, F1 did slip casting to raise productivity. they ground hongni to 100mu, but due to it being too sticky, method failed, the remaining materials were mixed with some zisha to give "niangao"

to which another person quipps :

这文章是拼凑许多行家早期发言的资料而成...或许其中有对有错. 注浆工艺在60年代由蒋容大师提议尝试后来失败.这是一事. 由红泥的残泥无意间拼配到紫泥形成咖啡色的年糕土.这是另一事.泥料因为再次磨碎变得更细密.是80年代初期出现的事. 以上这两事最初被认为有相关.但弟认为时间相隔20年.不太可能构得上关系. 至于紫砂的颗粒结构为多角型非圆珠型.能这是正解.....约5年小弟台湾手捏陶大师谢忠兴处得知并发表过. slip casting was initiated by Jiang Rong, but after some trials, it was considered a failed method in the 60s. between niangao clay and slip casting, there's at least 20 years apart between.

KZ's opinion : indeed there is 20 years between the material and slip cast attempt. so far F1 slip-casted pots appeared only between 1958 (might be slightly earlier) to 1960 and only several models were made, i.e. biandeng, roubing, xishi? Biaozhunhu from Taiwan had also investigated this issue when he had gone over to yixing to meet various former F1 artisans in the midst of compiling the new book on F1 花货. citing his investigation : 去年底也就是2014年底曾造访创厂元老黄月君先生（验坯、行政）所证实的，此作法的壶可以说都销往日本居多，而且产量极少，此灌浆技法当时1950年中期由来自景德镇二位制坯资深技师所传授，后来无法大量生产的原因是注浆之后还需要再修坯，未能提高产能，最主要原因是瓷土、陶土的泥性适合注浆，而紫砂先天土质不适合注浆（调泥繁复），因此产量极少，以上请参考。at the end of last year, I had the chance to visit and interview one of the founders of F1, mr Huang Yue Jun (QC inspections/administration), to which he confirmed that slip casting had been attempted before, with most of it being sold to japan, but very little numbers were ever made. the slip casting method in F1 was learnt from Jingdezhen in the midst of the 1950s, but due to post slip casting needing correction, the yixing materials unsuitable for the slip casting process, unable to increase productivity/production, the method was abandoned.

another theory :

清末民初朱泥,黄龙山朱泥,烧成后颜色略带土黄色,

文革时期因原矿数量稀少且成型困难,掺入部分本山绿泥制成年糕土取代
end qing to ROC, huanglongshan zhuni, when fired the color had some earthy yellew (really?!)... CR era, because real mined material is lesser, some benshan lvni was blended in to create niangao clay as a substitute.

yet another theory from the same person :

文革年糕土,由于粉碎技术的提升,

1964~1974年已经不需洗泥来取得朱泥,

所以整个原土粉碎的结果,将朱泥矿​​也粉碎进去了

这时期的土可以看出朱泥的含量很高,越是朱泥胎的土越Q润

during the CR, no one washed clay to get zhuni anymore, so the original aged clays have some zhuni content in them...

and to which another collector replied :

多年倒是没听说，可否说明来源出处？ 龙山名砂是前几年才听到有人炒作，可能是宜兴好的原土矿用尽，找些新花样 也可能是小弟识浅也说不定，兄有空可解一解小弟疑惑 早期年糕土中有混杂朱泥矿，这也是第一次听到，希望知道消息来源 若早期年糕土中有混杂朱泥矿，那更早之前甚至一厂前的红土壶中，是否也有可能含朱泥矿？that sort of blending was never heard of, do you have a source for the info? huanglongshan famous clays was only recently made into a hype and stirred, and to say that niangao contains zhuni, this is the first time! then how about the earlier era F1 hong ni, would it then have zhuni inside?

this is particularly confusing a matter during the early days of investigation. but it soon became clear if one looks at the mines to which the clays came from. zhuni was from zhaozhuang, xiaomeiyao etc, how would it be able to have been washed out from HLS mine well 1,2,3,4,5?