朱泥 (Zhuni): In the clay deposits of Yixing, there is a type of mineral called "nen ni" (tender clay), which is found in the surrounding mountains of Ding Shu Town in Yixing. The red clay mine is located at the bottom layer of the tender clay deposits. Over time, based on differences in the original mine layers and weathering levels, people have classified the red clay into three types: Zhu Ni (cinnabar clay), Xiao Hong Ni (small red clay), and Da Hong Pao Ni (big red robe clay).
Zhu Ni is considered a premium type of red clay with a higher iron content compared to other purple clay materials.
It primarily consists of red clay with a high iron content and is found in the lower layers of tender clay mines. It is also known as "unweathered stone bones" because it refers to clay that has not undergone complete weathering. The clay is as hard as a rock but disintegrates when it comes into contact with water. Although the supply of Zhuni clay has decreased, there is an unchanging principle: as long as red clay exists, Zhuni clay will not disappear.
Original Zhuni Clay: Zhuni clay is generally divided into three types:
1) red clay with a slight yellow hue,
2) yellow clay with a hint of red, and
3) red clay with a touch of purple (high-temperature Zhuni). Assessing the quality of Zhuni clay requires considerable experience. The effectiveness of the clay is mainly determined by its ability to release the tea's essence ("liquifying") and its smoothness. Zhuni teapots differ fundamentally from purple clay teapots.
Analyzing the finished product, Zhuni teapots exhibit a significantly higher degree of crystallization compared to red clay, and their firing shrinkage is more than 80% higher than that of purple clay (Zhuni: 18-27%, purple clay: 10-13%). Due to the high shrinkage rate, Zhuni teapots develop wrinkles or creases on their surfaces after firing.
Over time, these wrinkles become visible but cannot be felt by touch. This is why experienced teapot enthusiasts often say, "No wrinkles, no genuine Zhuni."
