Questions on Zhuni

[bonescwa]

Thanks! So not many pots that are younger than the 50s have that lid shape? I assume its commonly imitated?

[kyarazen]

Thanks! So not many pots that are younger than the 50s have that lid shape? I assume its commonly imitated?

early factory era i.e. '58 to early 60s may have some.

but its not commonly imitated, nowadays its hard to even seen a "puffed" lid shuiping clone. there are identification features to pots of a certain era, so in the modern day its hard to replicated, plus no one wants to hand make a shuiping pot anymore. probably wont be able to do it well either

[bankung]

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

[William]

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

I would say that normally are not fired twice nowadays. Firing a batch of teapots twice means higher cost than firing only one time.

[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.

[kyarazen]

Another question on Zhuni.

What is the shrinkage percentage after firing? Can the shrinkage be seen and identifiable in Zhuni as compared to other clay. What is the typical shrinkage pattern as compared to say Hongni? Lateral? patchy? grainy?

Is there any difference shrinkage pattern of different era Zhuni? And those fired in dragon kiln vs. coal kiln?

Thanks!

yoooo seem to ask very difficult but important questions that have bugged me for a while.. which make me wonder if you're an alterego or an emanation from my consciousness....


perhaps some potter can correct me here, but its been known that clays that are extremely plastic, usually shrink the most. but zhuni's kinda "defies" this logic, since its extremely non-plastic and.. yet it shrinks the most (up to 30%?!)...


for some of the authentic qing/roc zhuni pots i've seen, some of them are quite interesting that they dont exhibit very strong crumpling or immense shrinkage lines, the exteriors are jade smooth! there are others that have those shrinkage lines though, and some with very fine wrinkling on the surface as well.

this suggests a few things
1) perhaps the percentage content of zhuni is critical, and the plastic agent added is also critical
2) the firing method, since dragon kiln takes a long time to get the temperature up and a long time to get the temperature down, the gradual gradient may reduce the risk of busting a piece, unlike speedier methods. sudden expansion or contraction is the cause of cracking, not because the material cannot withstand the temperature (i.e 100 degrees hot water). steep gradients may also cause warpage or stronger/larger shrinkage marks


another question that came from a local collector, was there a specific kiln for zhuni pots, and if rare, scarce, premium stuff, where and how were they fired? and if in the qing, roc, etc there were high failure rates of firing, why wasnt there strong evidence of zhuni shards in old excavated kiln sites etc? what happened to the failed zhuni pots after firing? is there a historical record on how they were disposed/processed or even recycled?!

i now think of zhuni containing a special hydration state of a certain iron oxide type, that once in a wood fired kiln, during the cyclic oxidation/reduction, the reduction in the early stages turns this iron oxide type into FeO that fluxes extremely well. shrinkage is brought about by high amounts of fluxing, and if the material is homogenous, it might even shrink rather consistently.

Thanks kyarazen! Really appreciate your contribution. I don't think I have met anyone who identify himself/herself as kyarazen so far.

you should deem yourself very fortunate that you have not! HAHAHA!

[bankung]

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.

[AT333]

.... that are extremely plastic, usually shrink the most.

.... is there a historical record on how they were disposed/processed or even recycled?!

Thanks a lot kyarazen for your thoughts.

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?

Thanks a lot!

[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.

Please quote a source for this information. Otherwise, it is hearsay.

[Bok]

I don’t know how different the procedure is for Yixing pottery, but in regular pottery you almost always fire twice. You bisque-fire first in order to further clean and sand the pot, get rid of unwanted parts. Then you do the final firing, after which you sand and clean the pots again.

[Bok]

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.

That said, how would one even know if it was fired twice?
Is that even visible?

[kyarazen]

yup you're right. the early factory days went for single pass firing, so many of the pots are warped, lid fit not good etc. to get a very nice pot in single pass firing sometimes would mean the person whom made the pot has quite good skills and understanding on the material he works with.

2 pass firing is not a secret at all and it is perhaps even a norm for modern day. they call the 2 pass firing as 紫砂回窑 or 二次烧制

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.

[Tead Off]

yup you're right. the early factory days went for single pass firing, so many of the pots are warped, lid fit not good etc. to get a very nice pot in single pass firing sometimes would mean the person whom made the pot has quite good skills and understanding on the material he works with.

2 pass firing is not a secret at all and it is perhaps even a norm for modern day. they call the 2 pass firing as 紫砂回窑 or 二次烧制

Please quote a source for this. When did this become a norm? I don't think in the factory days they did this. In modern times, they have developed different techniques to fire, but when do 'modern times' begin in China?

[kyarazen]

Please quote a source for this. When did this become a norm? I don't think in the factory days they did this. In modern times, they have developed different techniques to fire, but when do 'modern times' begin in China?

2 pass firing is nothing new, tang san cai is 2 pass, so is all the glazed porcelains in song dynasty onwards etc. just that only in yixing ROC to F1 many times it was single pass, but did Shi Da Bin and others use two pass? no one knows, but his firing was perfect.

not necessary to quote a source in my point of view. it is a common process. if need be you can check out this link in chinese - http://lmgtfy.com/?q=%E4%BA%8C%E6%AC%A1 ... B%E7%A0%82

and if you read books on modern zisha artisans etc, it is also mentioned. on certain blogs and chinese forums there used to be debates on whether 2nd pass or 3rd pass firing zisha will affect the taste of the tea brew in it.

let us end our correspondence here.

[kyarazen]

That said, how would one even know if it was fired twice?
Is that even visible?

if the pot body does not require large amounts of correction nor any correction at all, then when 2nd passed it wouldnt end up with any major difference from a single pass, except that the porosity will be different, and the material will feel a bit more "dead" and a bit "over oxidized".

if there is correction being done, grinding, sanding, then the surface is re-coated with 泥桨 of the same type/color and re-fired to seal it.