Purple clay ore is mined from underground mines that are over a hundred meters deep. Whether it's purple, red, or green clay, it is all referred to as “raw material,” which is as hard as stone and requires a series of “clay refining” processes before it can become “raw clay.”

First, the materials must be selected and sorted in the mine field. They are exposed to wind, rain, sun, and night for months or even years, to decompose the ore into flaky pieces, a process known as “open-air weathering.” Once they have become loose small particles, they can pass through the feeding hole of a stone mill.

Removing impurities: The materials are selected, removing iron, limestone, basalt, and other impurities. A magnet is passed through the clay to extract iron-based impurities.

Mining and crushing the ore: The ore is ground into fine powder using a stone mill, which produces nearly round particles. Using these particles for making Teapots improves their breathability significantly. The powder is sieved according to the required mesh size of the clay, using screens of different specifications.

Adding water and mixing: Water is added to a large, round-bottomed vat for mixing. Purple clay is soaked and mixed with rainwater or mineral water. If tap water is used, the purifying agents in the water will form salt deposits on the surface of the clay during firing, causing discoloration of the finished product.

Refining the clay: Manual refining involves mixing dry powder with water until evenly blended, then using a wooden pestle or a stone roller to crush it until the cross-section shines and the clay is uniformly moist and pliable.

Forming wet clay blocks: Manually formed blocks are typically rectangular and about one foot long.

Aging and fermentation: Wet clay blocks are placed in damp cellars or within nested vats to age.

In the past, when Gu Jingzhou began experimenting with the use of Yellow Dragon Mountain No. 4 mine clay for making purple clay teapots, the raw clay did not look particularly vibrant in color, but because it contained natural sand grains, the Tea color would seep through the grains after long-term use, giving the Teapot a warmer, almost jade-like hue. This is considered the highest quality of clay, which has better breathability than ordinary clay.

Mesh Size

The texture of a Purple Clay Teapot is entirely determined by the mesh size of the clay. The larger the mesh size, the finer the sand; the smaller the mesh size, the coarser the sand. Some people prefer the refined and detailed appearance of finer sand, while others appreciate the rugged beauty and better tactile feel of coarser sand with a smaller mesh size.

To understand purple clay, one must grasp the basic concept of “mesh size.” After the purple clay ore is ground into powder, it must be sieved. A sieve with larger holes yields coarser powder, while a sieve with smaller holes yields finer powder. A lower mesh number means larger holes and coarser particles, while a higher mesh number means smaller holes and finer particles.

Clay with around 60 mesh is used to make teapots that, after firing, have both a fine texture and a sandy feel. The luster after seasoning and patination is good, and the water absorption rate is approximately 3% to 5%. It contains more crystalline phases of substances such as quartz, mica, and hematite, and fewer glassy phases, providing excellent shock resistance, breathability, and physical strength. It withstands sudden temperature changes, allows air but not water to pass through, and undergoes only favorable physical reactions when used for brewing tea. Currently, manually prepared clay has a mesh size of around 60, while mechanically prepared clay has a mesh size of 100 to 120.

Water is added, and the clay is aged and pounded, and it also undergoes “vacuuming,” which aims to increase the density of the clay and compress the spaces between the agglomerated and micro-particles.

(Mesh Size Reference)