Purple clay is professionally known in the industry as purple clay ore, commonly referred to as five-color soil, and also known as “heavenly blue clay,” “reddish-brown clay,” “base groove clear clay,” “bright red clay,” etc. Generally, it refers to the basic raw material for making purple clay pots, a specialty of Yixing.
It is found deep beneath the rock layers of Huanglong Mountain, between the “jia clay” strata. In Yixing, purple clay can be found in the clay mines within the Dingshu area. Products made from purple clay, such as purple clay teapots, rice cookers, vases, Tea sets, and other purple clay crafts, owe their popularity largely to the tea-drinking culture. A notable feature of the Purple Clay Teapot is that it does not overpower the aroma of tea and lacks a cooked scent; over time, even an empty pot will release a tea fragrance when filled with boiling water.
The Aging Process of Purple Clay
In the field of purple clay, aged clay is generally referred to as aged or seasoned clay. This process is also known as soil nurturing and is commonly called storing the clay. It is one of the processing steps for purple clay ore. After the purple clay ore is extracted, it undergoes sun-Drying, crushing, weathering, grinding, sieving, and mixing with water to form wet clay blocks about six inches wide and one foot long. These blocks are then stored in a dark, damp place (such as a cellar) that is neither exposed to sunlight nor air, while maintaining a certain temperature and humidity to improve the properties of the clay.
The primary values of aged clay include two points:
1. Enhancing plasticity during teapot making.
2. Reducing cracking during shaping and drying. The longer the aging period of the clay, the better the quality of the resulting purple clay teapot. In ancient Chinese Ceramic production, storing the clay for aging was considered a necessary step, with most aging periods lasting more than a year.
The belief among traditional collectors that products made from old clay are superior merely refers to differences in aging periods. Many enthusiasts have this misunderstanding. In reality, the formation of purple clay dates back tens of thousands of years, so it can all be considered old clay. Before making a teapot, the clay needs to be reconditioned. With a longer aging period, the purple clay becomes smoother and more pliable. Conversely, if the aging period is short, the clay appears dry and unappealing. Aged clay has a water-like appearance, making it visually pleasing. After being steeped and cared for, it becomes as smooth and lustrous as jade.
Aging is just one step in the processing of purple clay. Only through aging do organic compounds decompose into mature clay, which is easier to work with. It should be noted, however, that only high-quality purple clay, combined with a long aging period, can produce top-grade purple clay. If the clay comes from a poor-quality surface layer, no matter how long it ages, it will not be useful.
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