Hearing the term “old purple clay” gives one the impression that this is a type of clay with considerable pedigree. If you buy a Teapot made from it, you feel like you're getting your money's worth.

And while this is how it sounds, in reality, it's even more so!

What is Old Purple Clay?

The focus of old purple clay lies in the word “old.” There are several interpretations, including those that emphasize its high sand content and its long aging period.

High Sand Content

By “old,” we mean old chunks of purple clay ore with a high sand content. This type of ore contains many quartz particles, making the clay difficult to shape and requiring a high firing temperature when used to make Teapots.

Dingciaoqing (Bottom Trough Qing) is a typical example. With its high sand content, it sinks to the very bottom.

This interpretation suggests that due to its high sand content and difficulty in processing, it's described as old, hence the name Old Purple Clay.

Aging Period

By “old,” we refer to the aging time of the clay. Clay that has aged for a long time is called old clay.

Paste made from old clay has relatively higher plasticity and after firing, exhibits a relatively warmer luster. It becomes glossy and antique-looking after a short period of use and care. In a certain sense, the longer the aging period, the better, but clay that has been aged for too long needs to be reprocessed before making teapots.

This interpretation suggests that because of its long aging period, it's described as old, hence the name Old Purple Clay.

However, some old purple clays have characteristics very similar to those of old clays. Whether in use or during the care process, they are water-lubricated and develop patina easily, with little difference from the former (most current old purple clays fall into this category).

The Color of Old Purple Clay

There's no definitive explanation within the industry regarding old purple clay. The two interpretations mentioned above are considered more scientific.

Based on these two explanations, apart from having a high sand content and being easy to care for, old purple clay does not exhibit a specific color!

In summary, dark purple clay is not necessarily old purple clay. This is something pot enthusiasts must clearly understand.

The color of a zisha teapot only relates to the ratio of its clay mixture and the firing temperature.

Moreover, old purple clay is a type of old clay within the broader category of purple clays (in other words, purple clay that has been aged for a long time). Therefore, purple clay encompasses a larger range than old purple clay, which falls within its scope.

The relationship between the two is one of inclusion rather than distinction. Clays that have been aged for a long time are easier to care for and develop patina quickly.

The aging period of clay is, in a certain sense, better if it's longer, but clay that has been aged for too long needs to be reprocessed before making teapots.

Aging is not simply about “long-term storage,” but involves placing wet clay blocks in a cellar or earthenware jar that is shielded from sunlight and air circulation. Temperature and humidity must also be controlled to facilitate the generation and release of humic acid.

Most aging periods require 12 months to produce clay with evenly distributed moisture, fully decomposed organic matter, enhanced plasticity, and the ability to form without cracking, commonly known as “aged clay,” also referred to as “raw clay.”

Aged and fermented clay is called “raw clay,” and this “raw clay” must then be mixed by the master on a clay slab with leftover “ripe clay scraps” from previous batches, undergoing repeated kneading to become “ripe clay” suitable for making teapots, achieving the desired plasticity and uniformity.

Characteristics of High-Quality Old Purple Clay

1. Old purple clay possesses the general characteristics of high-quality purple clay, meaning that old purple clay is itself a high-quality purple clay.

2. After a long aging period, old purple clay contains more Pectin, making it easier to shape into teapots and developing patina quickly. High-quality purple clay is a “sand-rich” ore, containing many quartz particles. When normally aged and processed into clay, it is difficult to shape and requires a high firing temperature when used to make teapots.

3. Both old purple clay and high-quality purple clay are fast in developing patina and have good breathability. High-quality purple clay typically undergoes a long aging period, and the aging period of old purple clay is also longer than that of regular purple clay.

So sometimes, when we think about the time it takes to shape a zisha teapot, it might seem very brief, but behind it lies years of dedication.