Tiaosha and Pear Skin Zhuni

 Pear skin zhuni teapot. Photo from 阳羡茗砂土。

Where does Pear Skin Zhuni come from? How is this texture created?

Sometimes marketed as being an exotic variety of zhuni clay, or old storage “lao” zhuni clay, pear skin zhuni is produced through a very old technique that is still practiced in Yixing today called 调砂 Tiaosha.

Tiaosha

Tiaosha is a technique for processing Yixing clay that uses both 生砂 shengsha "raw clay" and 熟砂 Shousha "cooked clay." Shengsha refers to clay that hasn’t been fired (including bisque firing) yet. Shousha clay has been bisque fired at temperatures between 600-800°C, and then crushed back into sand at the desired grain size or mu 目数. 

Tiaosha is used to increase the plasticity of the clay, firing success rate, and to create a desired texture and appearance.

Bone and Meat 

When processing Yixing clay, potters will describe the clay in terms of 骨和肉 “bone and meat,” the sandy grains of the clay, as well as minerals like mica, are referred to as the “bone” which give the pot structure, and the smoother more “clay-like” part is described as “meat” which fills out the structure.
 
Zhuni has less “bone” than other zisha. Shousha is a way of creating this “bone,” sandy grainy content, through pre-cooking the clay. This clay is then mixed with the raw clay, shengsha, to give the pot both bone and meat.
 
The tiaosha technique can be traced back to the Ming Dynasty. There are records of the Ming Dynasty Yixing Teapot Potter, Shi Dabin 时大彬, using the tiaosha technique for his teapots.

2 Types of Tiaosha 

Tiaosha clay is produced in two different ways:

1) The same kind of clay consisting of shengsha and shousha, mixed together. Pear skin zhuni 梨皮朱泥 is an example of this type of tiaosha.

2) Different kinds of clay, shengsha and shousha, mixed together.  Examples include: zini 紫泥 shengsha mixed with duanni 段泥 shousha; duanni 段泥 shengsha mixed with hongni 红泥 or baini 白泥 shousha.

Benefits of using the Tiaosha Technique

Zhuni has less “bone,” than other types of zisha, and tiaosha is often used to give zhuni greater structure, making it easier to shape, especially when making larger teapots. 

Tiaosha is also used to help reduce the overall shrink rate of a teapot, especially in the case of zhuni which has a very high shrink rate. Using shengsha zhuni is more difficult, as the chance of the teapot breaking in the kiln is higher. Using shengsha zhuni requires a skilled potter and quality clay to reduce the risk of an unsuccessful firing. Using Tiaosha zhuni helps to reduce this risk, by reducing the overall shrink rate, as the pre-fired component, the bone, has already undergone shrinking in its bisque firing.

 Tiaosha is also used to create a specific texture or appearance. Potters seeking a contrast between large bumpy grains and smooth clay will use large grained shousha in their tiaosha mixture.

 Lipi Zhuni or Pear Skin Zhuni 梨皮朱泥 is a good example of this technique being used for a specific quality or aesthetic.

Ziyujingsha 紫玉金砂 “purple jade golden sand” is another example. It’s the result of zini shengsha mixed with duanni shousha.

An example of Purple Jade Golden Sand Clay.  Photo from 阳羡茗砂土。

Tiaosha or Shengsha? 

Some potters prefer to use shengsha. Lin Hanpeng prefers unmixed clay and the quality and consistency of original ore shengsha zhuni.

All of our Yixing Teapots come with studio certificates giving the production details for each teapot.

The certificate above lists: 1) the shape, 2) the material, 3) date of production, 4) the artist. The material description will list the kind of clay, whether it is original ore or not, and whether it is 调砂 tiaosha or 生砂 shengsha.

The certificate above is for a zhuni longdan teapot and lists the material as: 原矿朱泥 (生砂),  yuankuang zhuni (shengsha) original ore shengsha zhuni.

References

宜兴紫砂矿料 by 朱泽伟  等 Yixing Zisha Mineral Material by Zhu Zewei et al.

阳羡茗砂土 by 刘玉林 等 YangXian MingShaTu by Liu Yulin et al.