Some enthusiasts ask: What is meant by ‘oiliness'? Why does a brand new, uninitiated Teapot have such a smooth and glossy surface? What's going on here?

Where does the oiliness of a Purple Clay Teapot come from?

High-quality clay naturally contains oiliness. If you repeatedly smooth out a cross-section of good ore, you will faintly see some oiliness, similar to jade, where high-quality jade is naturally lustrous and over time becomes like sheep fat. However, lower quality jade will never achieve this effect no matter how many years pass. The same applies to purple clay.

The Jiangnan region has abundant water systems, and the ore beds deep beneath the mountains have been nourished for hundreds of millions of years by cold, clear spring water. Each piece naturally carries a glaze-like layer, as luminous and radiant as the inner wall of a shell, which is fundamentally different from shallow surface clays, much like the distinction between seed material and mountain material in Hetian jade.

A teapot made from high-quality clay doesn't need to be steeped in Tea or handled; it only needs to be rinsed with boiling water and occasionally wiped with a tea towel, and over time, it will develop a luster that is restrained and smooth like jade.

The texture of a good teapot becomes noticeably smoother when it comes into contact with hot water, then returns to its original state after being put away.

The true oiliness of purple clay is inherent and is brought out through the stimulation of hot water, becoming more evident over time.

Why does purple clay have natural oiliness?

This is closely related to its formation, which occurred in inland lakes with large amounts of shell and organic matter deposits. As a result, the ore contains many impurities and has been continuously saturated and eroded by groundwater over hundreds of millions of years. In contrast, most of the clay ores found outside the mountains are located on hills and are dry and pure.

Does the oiliness come from the tea?

Many enthusiasts believe that the reason why a purple clay teapot can develop a patina is due to the presence of tea oils in the tea leaves, but this is not the case.

Teapots made from many non-native clays are very dry and lack internal smoothness, and can only acquire surface oiliness through external absorption of tea oils.

Such teapots develop a superficial luster, lacking the depth and warmth that emanates from within. Of course, the luster also depends on the degree of vitrification after firing, the polishing process, and the use of glazes.

(For those who cannot distinguish between a superficial and a restrained luster, it is necessary to handle physical examples and make comparisons. It is often difficult to tell the difference from videos and photos alone.)

How to distinguish?

The oiliness of a purple clay teapot is inherent. Other characteristics of purple clay can be artificially adjusted, but oiliness is difficult to alter.

If the ore has good oiliness, the teapot made from it will also have excellent oiliness. During the nurturing process, the oiliness is simply brought out, enhanced by the oils in the tea seeping onto the surface and forming a natural patina.

Teapots with poor oiliness can only rely on the external absorption of tea oils and hand oils to form a false patina, which lacks depth and stability.

Each type of clay is unique and requires hands-on experience, gradual comparison, and feeling.

Lower quality clays, due to insufficient sand particles, have a very shiny surface, and when nurtured, they produce a reflective glass-like surface without any change inside.

Many sellers use finely ground clays to make teapots and then polish them to make them appear bright, which is a false patina.

Good clays, due to their adequate sand content, cause the surface to scatter light diffusely, making it comfortable to look at. During the nurturing process, one can clearly feel the changes, not just the surface patina, but also the texture, color, and feel of the interior, all of which evolve over time.

There are many criteria for evaluating purple clay, so even if a teapot has natural oiliness, it is not necessarily the best; oiliness is just one of many standards, and a comprehensive evaluation is required.

Is the “oiliness” of a purple clay teapot indicative of better clay quality? Consider the following four aspects:

1. The source of the mine (in general, for the same type of clay, native clays tend to have greater oiliness than non-native materials).

2. The aging time of the clay (theoretically, for the same type of clay, longer aging times result in greater oiliness than shorter aging times).

3. The skill of the potter in smoothing the clay (for the same teapot, a well-executed smoothing process results in greater oiliness than a poorly executed one).

4. Firing (in general, for the same teapot, firing three times results in greater oiliness than firing only once). Note: It is not the case that more firings are always better.

Images courtesy of ChaWo Network