Benshan lüni, benshan duanni, huangjin duan, other Yixing clays (zisha) that are light-colored or yellow-toned after firing fall under the umbrella category of “duanni” clay. Duanni is the third broad category of Yixing clays which include Zini (all purple Yixing clays) and hongni (red clay, which also includes zhuni).
Although there are various subgroups in this category, they share a number of important features. The original ores (原矿yuan kuang) in this category tend to be light grey, greenish-grey, grey with red or brown spots, and are comparatively softer and crumbly. The percentage of iron oxide in duanni is lower at usually around 2% (and no greater than 4%), compared to zini at 7-8% and hongni at around 10%. Firing temperature for duanni is between 1117-1200°C.
What are the differences between clays?
The broad category includes numerous clays, some with little visible differences, some quite different in color and feel. Some of the more popular varieties in the market include: Benshan lüni, benshan duanni, huangjin duan, and mo lüni
Benshan duanni 本山段泥
Benshan duanni originally referred to the duanni mined from Huang Long Mountain 黄龙山 in Yixing, but now it is also used to refer to duanni which has a light yellow tone, but which isn’t as light or soft as benshan lüni. Benshan duanni original ore contains both lüni and zini. It is darker than benshan lüni and often has a rougher or sandier texture.
Benshan lüni 本山绿泥
Benshan lüni ore contains only lüni. The original ore is greenish grey (lüni 绿泥 means “green clay”). It has a very low iron oxide content even for duanni. When fired it has a very soft pastel yellow tone.
Huangjin duan 黄金段
This clay is called huangjin 黄金or gold duan because it has a golden tone after firing. Huangjin duan is a thin layer of duanni that is found just below the surface of the mountain. It is quite rare compared to other duanni ores.
Mo lüni 墨绿泥
Mo lüni is a fairly common clay in the market. Its name translates to “green ink clay” because of its dark green appearance after being fired. This clay is in fact a mixture of clays and one or more colouring agents. There is no original ore that will turn green after being fired. This clay usually consists of the clays benshan lüni, bai duan, as well as the colouring agents chromium oxide and/or cobaltous oxide. True mo lüni clay following the above formula is safe to use. There are many fake green teapots that use other chemicals (some dangerous) to replicate the color of this clay. We advise caution when purchasing a green Yixing teapot.
What is duanni good for?
As always, we advise trying your teapot with different teas to see which combination you prefer. In general, duanni teapots are more porous/absorbent than other Yixing clays, and tend to retain heat longer. They are good for teas that like more heat for a longer period (like shu puer) and they are good for absorbing the unpleasant flavours of some teas (hints of smoke). We like them for shu puer, very strong semi-aged sheng puer, and some high roast wuyi wulong teas.
When describing what a real Yixing teapot looks like, many collectors are at a loss to put into words what distinguishes a real Yixing clay (zisha) teapot from other clay teapots; they just know when they see and feel the teapot for themselves.
Fortunately, Besides the texture and color of the teapot, there are a number of signs or ‘imperfections’ that can be looked for to indicate the authenticity of an Yixing Teapot. There are four kinds of ‘imperfections’ which can be found on true zisha: 1) Tiny white spots; 2) Tiny black spots; 3) Tiny holes on parts of the surface; 4) Tiny bumps on the surface.
Tiny White Spots (Mica)
Zisha contains many naturally-occurring minerals including: hydromica, muscovite, kaolinite, quartz, hematite, iron oxide, silicone oxide and others. Their inclusion in the clay and the firing temperature of the teapots (generally between 1050°C - 1280°C) give it its special appearance.
The tiny white spots are trapped particles of mica. Mica will not vaporize below 1280°C, so these spots are a common characteristic of the surface of Zisha teapots.
Tiny Black Spots (Tierong)
The tiny black spots are called Tierong 铁熔 in Chinese. They are caused by the melting and separating of iron from the clay during the firing process at a high temperature. The iron forms small black spots on some parts of the surface of the clay. These iron spots should appear as tiny spots that are scattered few and far between. If the surface has a great many black spots crowded together, it’s a sign of low quality.
Tiny holes on the surface (Tiaosha)
If you look very closely at the surface of an Yixing teapot, sometimes you will be able to see a few very tiny holes. They are so small and few that they can go unnoticed.
These holes are called Tiaosha 跳砂 which translates to “jumping sand.” This is a result of the sand-like character of zisha. When firing in a kiln, all zisha will shrink in size to a certain extent, during shrinking, some larger grains of zisha on the surface of the teapot are sometimes squeezed until they pop off of the surface, leaving a tiny hole. This is a sign of true zisha, unmixed with other kinds of clay.
Tiny Bumps on the surface (Baozi)
Tiny bumps, found scattered on the surface of zisha, are called baozi 爆子. These bumps are caused during firing in the kiln when the size of the teapot contracts. Some larger grains of zisha inside the surface of the clay are squeezed and pushed out towards the surface of the teapot. These grains are blocked by the surface clay, which is pushed outwards forming a bump.
All four of these ‘imperfections’ are in fact indicative of authentic zisha. When found together they indicate a very high likelihood that the clay is authentic pure zisha (not mixed with non-zisha clay). Since these characteristics are very difficult to fake, they are used as a guide to evaluate the authenticity of Yixing teapots.
by Patrick and Siyan
We continue our series on Yixing clay, also known as zisha, by looking at Dicaoqing 底槽青, a kind of zini 紫泥 or purple clay.
Dicaoqing is one of the most well-known kinds of zini. It was originally mined from the now-closed no. 4 and no. 5 mines in Huang Long Shan 黄龙山 and is found when mining other zini. The ore of dicaoqing is easily identified by greenish grey spots, referred to as “chicken eyes” 鸡眼 jiyan. The low amount of oxidized iron in these areas causes the greenish discoloration in the ore.
What’s in a name?
The name for dicaoqing comes from where the miners would find dicaoqing while mining zisha ore. After deciding where to dig, zisha miners would dig out a trench or “trough” (槽 cao) to mine the ore. The common name for zini at that time was “qingni” 青泥. Dicaoqing was found at the bottom (di 底) of the trench (cao 槽) of qingni (青泥). The name dicaoqing 底槽青 roughly translates to “at the bottom of the qingni trench”.
Red or Purple
One of the interesting things about dicaoqing (although not unique to this clay), is how firing temperature affects the final color of the clay. The firing temperature for the clay is between 1150-1250°C. Between that range the color of dicaoqing changes drastically. Firing at a lower temperature, such as around 1150-1170°C results in a dark red that can be described as sienna or “pig liver red." Firing at a higher temperature results in a much darker color, closer to dark brown/purple.
A Clay for a Versatile Teapot
Dicaoqing can be used like a zini clay teapot. Zini or purple Yixing clay is favored by Chinese tea drinkers because of its versatility. Not as porous as duanni, but more porous than zhuni, dicaoqing, like all zini clay teapots, is seen as a good clay for most kinds of tea. We find that sheng and shu puer, green oolong, yancha, black tea, all do well in this kind of clay.
This is part 2 of our article about Zhuni Clay, a kind of Yixing clay or zisha used to make teapots in the town of Yixing, China. In this two part article we answer some of the more common questions we have received about this clay. To read the first part of our article, click here.
What is “Old Zhuni”?
When distinguishing “old zhuni” from “new zhuni” we first need to distinguish “old zhuni” from antique zhuni. “Old zhuni” lao zhuni 老朱泥 is a term from the zisha industry that refers to how long zhuni clay has been aged before it has been shaped into a teapot and fired. All zisha clay, zhuni included, has to be aged before it can be used. Aging the clay means that after the ore has been mixed with water and processed, it will be allowed to sit so that the organic matter in the mixture decomposes and ferments. Whether zhuni is old or new depends on how long it has been left to ferment. Zhuni left for 1-2 years is “new zhuni” xin zhuni 新朱泥. Zhuni left for 3 or more years is “old zhuni.” “Old zhuni” continues to be used today in Yixing. This is different from antique zhuni, which refers to zhuni teapots made long ago.
The zhuni that Wuyou Hall use to make the Yixing teapots we carry was stored for over 5 years and is old zhuni.
Is Zhuni Extinct? Did they close the mine?
We are often asked whether real zhuni is still available or whether it is “extinct.” Zhuni is not extinct, but it is rare. The myth of its extinction comes from the restrictions on zisha mining. Fear of overmining and environmental degradation led the Yixing government to greatly restrict mining operations beginning in 2005. All official mines were either closed or had their operations limited. This includes operations in the famous three spots: Huang Long Shan 黄龙山, Zhaozhuang 赵庄, and Xiaomeiyao 小煤窑.
Despite these restrictions, mining of zisha continues to this day. Zisha is still mined to a limited extent from official mines, but also from mines on the outskirts of Yixing, from construction and infrastructure projects in Yixing, and from “unofficial” mines in the town. The large amount of clay mined up until 2005, the need to age zisha before use, and the large size of the industry relative to the town, means that a certain amount of clay has survived in storage. This includes zhuni. A small amount of zhuni continues to be mined each year as well.
Zhuni is scarce compared to other zisha and it is in the interest of the people who sell the clay and make it into teapots to exaggerate how rare the material is. Stories that zhuni is extinct - except for a small amount that was hidden away by this one studio - circulate in order to drive up the price of teaware being sold.
How rare is Zhuni?
If we take Huang Long Shan as an example: Only 3-5% of the mountain is made up of Zisha ore; within that zisha ore, 80% is zini or purple clay, 12% is duanni, and only 8% is hongni. Zhuni makes up only a small amount of that hongni. It is still available and it is still being mined, but it is a very small proportion of the total amount of zisha ore being mined.
Within that tiny amount of zhuni there is an even smaller percentage that is “Da Hong Pao” zhuni, an extremely sought-after and extremely rare clay. It is estimated that around one in a million “Da Hong Pao” teapots being sold in the market are authentic.
How to avoid fakes?
There are lots of fake Yixing teapots in the market, and zhuni teapots are no exception. Because Zhuni ore is rare and very little is extracted each year, many fakes have flooded the market. These fakes attempt to mimic the appearance of zhuni using non-zisha clay, impure clay, chemicals and coloring mixed with real zisha or other clay.
Some of the fakes are easy to spot, others less so. Teapots that look very shiny before they have been used, that feel sandy or muddy to the touch, that have a bad or chemical smell, should all be avoided. Other selling points that sound too good to be true are also red flags. If a zhuni teapot is being sold for $50 USD or less, there is probably something wrong with it.
Fakes that use zisha clay mixed with some chemicals, other clay or coloring are harder to spot for someone who hasn’t used a real zhuni teapot before. Before getting into this business we had the misfortune of buying a fake zhuni teapot. It wasn’t until later when we had a lot more experience and were able to compare it to a real zhuni teapot that we noticed the texture and feeling wasn’t quite right. We stopped using the teapot as there is no way of knowing what was used to make it. After a long time looking at different teapots on the market, studying up on zisha and asking around and meeting with different studios we began to have a better understanding of the process of making Yixing teapots and of how to distinguish genuine Yixing and Zhuni from the fakes. After getting to know the owners of Wuyou Hall, seeing and using their teapots and observing their process, we decided to choose them as our suppliers because we know the products we are providing are genuine, safe, and a pleasure to use. The Yixing teapots, including a zhuni shuiping that we use daily, were all made by this studio.
Is Zhuni a mixture of clays? What is “original ore” zisha clay?
Original ore zisha refers to zisha clay that only contains zisha clay and is not mixed with any other kinds of clay, chemicals or coloring. It is safe to use.
At this point it is important to discuss mixing clay. It is important to distinguish between zhuni mixed with other zhuni clay, mixed with other zisha clay, and zhuni mixed with non-zisha clay and/or chemicals and coloring.
Different kinds of zisha clay are often mixed together before being processed. This is a normal practice in the industry and goes back hundreds of years. The people who process the raw ore before it is sold to potters often have recipes passed down through generations to produce zisha that will yield the desired textures, colors, characteristics sought by the potter and by the customer. Zisha mixed in this way is perfectly safe and does not have any harmful chemicals. Real zhuni used for teapots in the past and today, consists of clay that may be 1) zhuni ores from different mines mixed together (Huang Long Shan + Zhaozhuang + other mines), 2) processed zhuni mixed with unprocessed zhuni, 3) zhuni mixed with small amounts of other zisha (such as hongni). All of these processes are safe to use, however mixing with other kinds of zisha clay is perceived to have a negative effect on the texture, shine and character of a zhuni teapot.
The desirable and common way to mix zhuni is by using different sifters to sieve zhuni ore into different sized particles. Clay that is mixed in this way will show larger particles in the skin of the teapot (the different sized particles in the zhuni clay are referred to as “bones” and “meat”). If it is good quality zhuni, then no other mixing is necessary.
The zhuni teapots we sell are 100% pure zhuni.
The world of Yixing Teaware is full of myth, misconception, and exaggeration. It can be quite challenging for someone new to Yixing teaware to make an informed decision when purchasing a teapot. Of all of the Yixing clays, perhaps the most mysterious is Zhuni, the famous orange-red clay. A great deal of misinformation standing in for factual information makes it difficult for anyone who is interested in acquiring a zhuni teapot. We often receive questions from customers about this clay and will do our best to answer some of the most common questions below.
What is Zhuni?
Searching for information online one finds confusing talk of “old zhuni” vs “modern zhuni,” of zhuni being “extinct,” and the claim that “modern zhuni” is in fact “hongni” or a mixture of hongni and other Yixing clay.
If we are using the original definition of “hongni,” then zhuni is a kind of hongni. Hongni 红泥 means red clay and was used to refer to Yixing clay that was red in color after being fired in the kiln. The charater 朱zhu in zhuni refers more specifically to vermillion or cinnabar red, a bright-orange red hue. The term zhuni was applied much later to some hongni teapots that exhibited a number of characteristics that were much sought after for a group of Yixing teapot collectors. Hongni teapots that were bright orange-red or zhuhongse 朱红色 and which appeared somewhat silky to the touch and gained a brilliant shine from use, came to be called “zhuni” 朱泥in contrast to the other darker, rougher hongni clay.
Zhuni can also be separated from hongni from the appearance of its raw ore and from where the ore is mined. Zhuni ore comes from soft mudstone, hongni is a kind of sedimentary rock. Zhuni ore is fragile and when mixed with water is very smooth. Hongni is harder and sandier.
Hongni and Zhuni react differently when fired. All zisha will contract / shrink to a certain extent when fired in a kiln, but not all shrink to the same extent. The shrink rate of hongni is about 13%, however zhuni will shrink from 17-25%. The high rate of contraction means that zhuni is more likely to break in the kiln, and fewer zhuni teapots survive firing than other kinds of zisha. Although modern techniques allow the artists to optimize the process, making it possible to fire more pots without losing as many of them in the kiln, and even to make larger teapots, most studios still err on the side of caution and avoid making larger zhuni teapots, as they are more likely to break in the kiln. Most zhuni teapots are 160ml or smaller.
What kind of tea is good in a Zhuni Teapot?
Yixing Teapot tea pairing is very subjective, however it is generally agreed that Zhuni is better than other other kinds of Yixing clay (known as zisha) for fragrant teas, like Taiwan high mountain oolong. It works well with black teas and other higher roast oolongs as well. Compared with other zisha, zhuni is denser, has smaller pores, and traps less air between its pores. As a result, it is better at conducting heat and does not absorb fragrance as much as zini or duanni. The result is that it acts more like porcelain, losing heat faster, so it doesn’t overcook more delicate teas, and it holds the fragrance, concentrating it, unlike zisha such as zini and especially duanni, which are often favoured to help “round out” a tea with harsher notes, like a young strong sheng puer.
What is 'Old Zhuni'? Is Zhuni 'Extinct'?
Is Zhuni mixed with other clays?
How to choose a Zhuni Teapot?
Find out the answers to these and other questions in Part 2 Here.
Kilns using wood as fuel have become increasingly scarce in modern China. With the adoption of easier to use and less-costly electric kilns, very little teaware is still fired in traditional wood fuel kilns. While Yixing Teapots fired in electric kilns are beautiful, there is something special about wood-fired teaware, especially wood-fired teaware that is fully exposed to the fire and ash during the process.
Traditional and Modern
Prior to the adoption of electric kilns, Yixing Teapots fired in wood kilns were often put into boxes to prevent the interaction of ash with the clay during firing. This was done to preserve the uniform color and appearance of the surface of the clay.
Naked Wood Fired teapots are placed directly into the kiln without any covering to allow the interaction of wood fire and ash on the surface of the clay, giving each piece a unique pattern, color, and texture.
The Pine wood used as fuel turns to ash and falls onto the surface of the teapots during firing, melting and forming a glaze of various colors and patterns over parts of the surface. This is called “naturally occurring ash glaze.” The process results in different color patterns and a striking shine unlike that found on teapots fired in electric kilns.
Wood Kiln Firing Process
Unlike Yixing Teapots fired in electric kilns, which are typically fired for one day, wood fired Yixing teapots are fired in a lengthy process spanning almost a week:
1 day of firing in electric kiln
After the Yixing Teapots are shaped by the artist, they are placed in a modern electric kiln for the first phase of firing. This phase dries out the clay, removing all moisture. This initial phase requires precise conditions and temperatures to prevent any damage, cracking or structural weaknesses. Electric kilns provide more precise controls and are therefore used for the initial phase.
3 days and 4 nights firing in wood kiln
The teapots are removed from the electric kiln and then placed in a wood burning kiln. The kiln uses local pine trees for fuel. The kiln is fed pine tree logs, slowly bringing the temperature inside the kiln to 1200 degrees Celsius. The teapots are then fired for 84 hours (or 3 days and 4 nights) at this temperature. This process changes the composition and appearance of the teapots. Firing at this high temperature for this length of time removes organic compounds and other unwanted elements and produces a stronger surface. The interaction of the ash which falls on the teapots during firing produces beautiful patterns called “ash glaze”. When the teapots are removed from the kiln their patterns and colors are set, but they have a rough appearance on the surface.
1 more day of firing in electric kiln
Firing in an electric kiln for one additional day removes the roughness from the surface of the teapot, giving it a more finished appearance. The teapots are now finished and are ready to be used.
Using your Wood Kiln Yixing Teapot
All Yixing Teapots need to be prepared properly before use to remove unwanted dust acquired during firing. This is true of wood kiln Yixing Teapots as well as those fired in electric kilns. Teapots should be rinsed thoroughly in warm water 2-3 times and then rinsed at least 3 times with boiling water. We do not recommend boiling your pot as agitation will likely result in cracking and chipping! Once the teapot has cooled down, add tea, add water and enjoy.