The Causes and Removal of “Black Spitting” on Purple Clay Teapots

After a certain period of brewing, parts or the entirety of a clay may darken, which is commonly referred to as “black spitting.” This “black spitting” can be relatively uniform across the entire surface of the teapot, appear in streaks, or concentrate in specific areas (commonly seen along the lid rim and bottom edge of the teapot).

The Causes and Removal of

The causes of “black spitting” on purple clay typically fall into two categories. The first situation occurs when the clay body is not fired at sufficient temperature (underfired), causing the clay particles to contract incompletely. This results in the body's pores being too loose and large, allowing tea's chlorophyll and iron ions to seep into these pores and create a different hue from the body of the teapot.

Different clays and techniques require different firing temperatures. Sometimes, if the temperature is not high enough or the duration is slightly shorter, the clay does not fully contract. In such cases, where the teapot exhibits obvious localized “black spitting,” the “black spitting” on the teapot will be more noticeable.

This only indicates that there may have been flaws in temperature or time control during firing, and it has little to do with the potter's skill.

The Causes and Removal of

Currently, all purple clay teapot kilns in are privately operated. Typically, potters can only specify the firing temperature and duration for their pots but cannot control the actual firing process. Moreover, slight variations in temperature are undetectable in the finished product itself.

Therefore, even master-level potters cannot guarantee that their teapots will not exhibit localized “black spitting.” It can be said that kilns may pay more attention when firing the works of masters, but that's about it.

The second situation is that those who understand purple clay teapots know that they are called “sacred vessels for brewing tea” due to the unique double-pore structure that develops after high-temperature firing. This structure allows the teapot to breathe well and retain heat. The “black” is actually tea residue and iron ions from the tea. During use, this residue remains in the invisible pores on the surface of the teapot, while iron ions from the tea also settle within these pores. Over time, “black spitting” forms.

The Causes and Removal of

Theoretically speaking, any purple clay teapot will “spit black.” All types of clay will show some degree of black spitting over time, unless the material itself is not purple clay. The longer a purple clay teapot is used for brewing tea, the darker its color will become. However, the extent of “black spitting” varies depending on the color of the teapot, the location of the “black spitting,” the type of tea brewed, and the user's experience in caring for the teapot. Some “black spitting” is imperceptible to the naked eye, while other instances are more obvious.

If the teapot's color darkens evenly, it should be considered a positive change. However, whether the “black spitting” is even largely depends on the user's habits in caring for the teapot. When caring for the teapot, apply tea juice evenly, clean it thoroughly after each use, and gently wipe it with a soft cloth. Gradually, a luster will appear. Some people may dislike the effect of localized “black spitting” on a purple clay teapot, feeling that it detracts from its appearance. However, on the other hand, “black spitting” indirectly proves that you are using a genuine purple clay teapot.

The Causes and Removal of

Misconceptions About Black Spitting:

Is “black spitting” harmful to health?

Understanding the composition of the “black” makes it clear that “black spitting” is completely harmless to the body. Some people may dislike localized “black spitting” on a purple clay teapot because they feel it detracts from its appearance. However, on the other hand, “black spitting” indirectly proves that you are using a genuine purple clay teapot.

The Causes and Removal of

Does “black spitting” indicate that the purple clay teapot is fake?

All types of clay will exhibit some degree of black spitting over time, unless the material itself is not purple clay. The longer a purple clay teapot is used for brewing tea, the darker its color will become. Deeper-colored clays (such as purple clay) result in teapots where “black spitting” is less visible due to the already dark color of the body. Lighter-colored clays (such as duan clay) produce teapots where “black spitting” is more noticeable, and duan clay requires higher-temperature firing compared to other clays. Therefore, “black spitting” is more pronounced in duan clay teapots.

The Causes and Removal of

Different teas also produce varying effects of “black spitting” on the teapot. Simply put, lighter-colored teas result in lighter “black spitting,” while darker-colored teas lead to deeper “black spitting.” Therefore, generally, duan clay is more suitable for brewing Tie Guanyin and unsuitable for brewing dark tea. Unless, of course, you are seeking a special “black spitting” effect.

Methods to Remove “Black Spitting” from the Teapot:

Since the “black” is tea residue and iron ions, if you insist on removing the “black,” there are methods available.

As “black spitting” permeates the pores of the purple clay, regular cannot eliminate it. To remove it completely, the teapot must be refired. Refiring the teapot can remove the “black” since organic substances like tea residue and iron ions will burn off at high temperatures, restoring the teapot to its original appearance.

However, please note: First, ensure that the teapot is thoroughly dried before refiring, even then, there is still a risk of cracking. Second, there is a risk associated with refiring, with a damage rate of approximately 5-10%. However, after refiring and subsequent tea brewing, “black spitting” will occur again.

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