The mineral composition of Hong Ni (red clay) includes Illite, Kaolinite, Iron Oxide, Quartz, and Mica. The color after firing varies based on the iron content: it can be a red with a slight yellowish hue, a yellow with a slight red, or a red with a slight purple tone. The colors can range from vermilion to cinnabar purple or coral red, with a warm, glowing effect, showcasing a rich yet balanced tone. The color is deeply influenced by the firing temperature, and with prolonged use, it develops a more stable, subdued aura. The characteristic of Hong Ni is that it is red without being overly bright.

Zhu Ni (Vermilion clay) contains a very high iron content and is considered a premium within the Hong Ni category. The original mineral source typically lies between the clay layer on the mountain's surface or in layers of silt and soft mud, formed by the weathering of light-colored soft mud. The appearance is golden yellow or pale yellow-green, with a dense, lump-like or clumpy structure. The texture is relatively uniform and fine, generally containing small amounts of fine white mica fragments and about 14-18% iron oxide. It easily dissolves in water to form a mud-like paste, and the body is hard and solid. The color is a warm red with a hint of orange, offering excellent translucency and texture.

Differences between Zhu Ni and Regular Hong Ni:

1.Mineral Source and Clay Properties: Zhu Ni is mainly found in soft mud mines, while Hong Ni comes from layers of yellowstone deposits. Zhu Ni has higher clay content and weaker sand content, while Hong Ni has a more sand-heavy composition with weaker clay content.

2.Shrinkage Ratio: Regular Hong Ni has a shrinkage rate of about 13%, whereas Zhu Ni can reach a shrinkage rate of over 25%.

3.Color and Texture: Hong Ni offers a soft and gentle red tone with a slight orange hue. Zhu Ni is a bright vermilion with a subtle orange glow, possessing an exquisite, fine texture.

4.Forming Difficulty: Zhu Ni, due to its delicate nature, is more difficult to mold. Larger teapot shapes have a lower success rate, while smaller teapots are lively and cute in form.

In Yixing, there are various regions producing Zhu Ni, including Huanglong Mountain Zhu Ni, Qinglong Mountain Zhu Ni, Zhaozhuang Mountain Zhu Ni, Elephant Mountain Zhu Ni, Lanshan Zhu Ni, Small Coal Mine Zhu Ni, Wushan Old Rock Zhu Ni, and Xiangshan Zhu Ni. Additionally, within a region, there may be different mineral layers and varieties. Each mineral vein has a distinct mineral composition, and the fired teapots will have unique characteristics based on the specific mineral content.

1.Huanglong Mountain Zhu Ni

Huanglong Mountain Zhu Ni comes from a thin layer of oil clay between yellowstone and purple sand deposits on the mountain top. After firing, it is unpolished, presenting an orange-red color. However, it is in limited supply, and since the Ming and Qing dynasties, this clay was often mixed with Zhu Ni from other regions, such as Zhaozhuang, Shashan, and Hongwei Xiangshan, which produced Zhu Ni as the primary material. Its firing temperature range is narrow, generally around 1130-1140°C. The fired clay results in a dark red hue, with a pure and gentle texture, showing pear-skin-like surface particles that are subtle yet rich in color.

2.Zhaozhuang Zhu Ni

"Zhaozhuang" Zhu Ni, one of the most renowned types, is produced in Zhaozhuang Mountain in Ding Shu Town, Yixing, Jiangsu. Zhaozhuang is famous for its red clay, and Zhaozhuang Zhu Ni is a clay formed between rotten yellowstone and red clay deposits. It is rare, with a dark red color after firing. Zhaozhuang Zhu Ni has a high iron content, good air permeability, and a reddish, uniform texture. Its unique "pear-skin" pattern, with a delicate feel, makes it an ideal material for high-end tea wares. However, the firing temperature range is narrow, which can lead to defects such as deformation, wrinkling, or bubbling. It generally requires firing at around 1120°C. After firing, it appears red with a slight yellowish transparency, a fine and firm texture, and a pear-skin-like surface, rich in delicate color effects.

3.Xiaomeiyao Zhu Ni

"Xiaomeiyao" Zhu Ni, produced in the Huanglong Mountain mine area of Yixing, has a high iron content. After firing, it presents a reddish hue with a slight yellowish tone, exhibiting uniform texture, warmth, and delicacy. Small Coal Mine Zhu Ni has a significant shrinkage ratio, which makes it less prone to deformation. It is suitable for making various small teapots and cultural crafts. Its firing temperature range is narrow and can result in defects such as deformation, wrinkling, or bubbling. The firing temperature generally ranges from 1130-1140°C. After firing, the color appears red with a smooth and bright texture, showing a pear-skin-like surface with subtle, rich color effects.

Zhu Ni Characteristics and Tea Recommendations:

1.Unlike other Zisha clays, Zhu Ni has a larger clay content and less sand content, so the unique dual-hole structure of Zisha teapots is not as pronounced.

2.Zhu Ni has a higher density than other clays. When there is an abrupt temperature change, the lack of air pockets to buffer the sudden change may cause cracks.

3.Due to its significant shrinkage ratio, Zhu Ni teapots tend to develop wrinkles and are more prone to deformation. For this reason, throughout history, Zhu Ni teapots have typically been smaller in size.

4.Zhu Ni has a very high iron content, and if the firing temperature is too high, iron elements may be released, resulting in black iron deposits on the surface.

5.Due to its high density and small air pockets, Zhu Ni has no excellent breathability, enhancing the aroma of the tea. It is ideal for brewing lightly fermented, aromatic teas such as Taiwanese high mountain tea, Tie Guan Yin, Longjing, and black tea. Zhu Ni teapots have the ability to trap aroma, resulting in a tight, smooth tea broth with a long-lasting aftertaste.

More [ Zhu Ni Teapots ] here.

Zisha clay is primarily made up of three basic minerals: [ Zi Ni ], [ Lv Ni ], and [ Hong Ni ]. These three types coexist and form various mixed minerals, referred to as Duan Ni. In the following article, we will focus on the four most common types of Duan Ni: [ (Gold) Duan Ni ], [ (Cyan) Duan Ni ], [ Jiangpo Ni ], and [ (Yellow) Jiangpo Ni ].