Wood-firing: an ancient yet modern technique. Throughout China's thousands of years of ceramic production history, wood-firing was the sole method. Today, with advanced technology, ceramic firing techniques have diversified, yet the ancient wood-firing technique remains highly sought after.

What is Wood-Firing?

Wood-firing is an ancient firing method. Before the availability of coal, gas, or electricity, wood was the primary fuel for kilns. So how is wood-firing defined? Generally, any ceramic product fired using wood as fuel can be called wood-fired. These works can be divided into two categories: glazed (base glaze) and unglazed (natural ash glaze). For instance, Song Dynasty Tenmoku bowls and celadon are glazed, while Bizen ware from Japan is unglazed (relying on natural ash effects). Wood-firing is both an ancient and modern technique, and the success of a piece depends significantly on the relationship between the clay, fire, wood, and kiln. Is a wood-fired kiln the same as a wood kiln?

In modern parlance, what people often refer to as a wood kiln is technically not a “wood kiln”; the correct term should be wood-fired kiln. The true wood kiln was one of the Five Great Kilns of ancient China (Wood Kiln, Ru Kiln, Official Kiln, Ge Kiln, Ding Kiln), ranking first. It was established in 954 in Henan Province (some say Kaifeng) during the Later Zhou dynasty by Emperor Chai Rong, hence it came to be known as the Wood Kiln starting from the Northern Song dynasty.

Characteristics of Wood-Fired Kilns

Using wood to fire ceramics is distinct from modern gas and electric firing.

Ceramics are the perfect combination of earth and fire. Firing ceramics in a wood kiln versus a gas or electric kiln is like steaming buns using steam versus a microwave – one results in soft and tasty buns, while the other produces hard ones.

Traditionally, pine wood is used in wood kilns due to its high resin content. As the wood burns, the resin permeates the ceramics, imparting a nourishing effect. The principle of wood-firing involves gradually adding wood to increase the temperature, allowing the pieces inside the kiln to heat up slowly. Combined with the interaction of moisture and glazes, this results in ceramics with a subtle and nourishing surface finish.

Basic Requirements for Wood-Fired Ceramics?

Clay: Various types of clay (earthenware or porcelain clay, purple clay) can be used for wood-firing. Potters blend their own clays, considering factors such as the clay's heat tolerance, kiln characteristics, and type of wood. They aim to create a warm, thick, and restrained beauty.

Wood: Generally, wood needs to be seasoned for about three to six months (avoiding excessive moisture) to facilitate burning. Types of wood include pine, camphor, longan, lychee, loquat, and scrap wood.

Kiln: Heat is provided solely by burning wood. A typical firing lasts three to five days, requiring round-the-clock shifts to stoke the fire. Factors such as the speed and method of adding wood, the type of wood, weather conditions, and airflow all subtly influence the color changes in the kiln.

Ash: In wood-firing, completely burned ashes are very light and float with the hot air currents. When the temperature reaches above 1200°C, the ash begins to melt. Iron in the ash reacts with iron in the clay body to form a glaze, resulting in various color changes. This type of glaze is called “natural ash glaze,” which might not be immediately striking but grows more appealing over time – a charming aspect of wood-fired works.

The Kiln Structure of Wood-Fired Kilns

The structure of a wood-fired kiln typically consists of four parts: the firebox, kiln chamber, chimney, and flue.

The structure of a wood-fired kiln typically consists of four parts: the firebox (burning chamber), kiln chamber, chimney, and flue. The principle of firing is that the wood burns in the firebox, generating heat, ashes, and flames that pass through the kiln chamber and affect the clay pieces placed inside before being expelled through the flue. Therefore, the design focus must be on facilitating combustion (including heating and insulation), the effects of fire and ash on the clay bodies, and the path of the fire (side flame, inverted flame, or vertical flame).

Differences Between Traditional and Modern Wood-Firing?

In ancient times, wood-firing was an ancient firing method. Before the availability of coal, gas, or electricity, wood was the main fuel for kilns. When firing pottery, the ceramic body was covered with a saggar to separate it from the ash and fire, ensuring uniform glaze appearance.

However, under the highly successful modern pottery and firing techniques, a different “firing philosophy” for modern ceramic art creation has emerged, diverging from traditional wood-firing aesthetic standards. Modern wood-firing techniques pursue the natural combination of ash and clay, and a direct dialogue between clay and fire.

Why are Wood-Fired Kilns Pricy?

The cost of firing in a wood kiln is high, and the success rate is low. First, the government has banned wood-firing, and there is no supply of pine wood. Without dedicated funding and purpose, nobody would dare to fire a wood kiln due to the significant risks and costs involved. Second, nearly 3000-4000 pounds of pine wood are consumed per firing, making the cost quite high. Third, firing requires a team of experienced individuals to work together, as the kiln's temperature and timing are entirely dependent on manual control, especially the master in charge. A small mistake can lead to a kiln collapse, resulting in losses of tens of thousands of yuan. Fourth, the temperature varies within the kiln, with the front being hotter, the back cooler, and the middle most suitable. This results in significant differences in quality among the ceramics produced in the same firing, leading to a low success rate.

With advancements in modern technology, the firing methods for Yixing Teapots have become more diverse. However, traditional firing methods continue to be passed down due to their unique artistic charm, reflecting a nation's respect for tradition. Only by preserving the original essence of tradition and building upon it can we continuously advance the craft of ceramic making.

Wood-firing is a way of firing ceramics; compared to modern gas, electric, and coal kilns, it is a very traditional and even ancient method. Due to the efficiency, convenience, and cost-effectiveness of gas, electric, and coal kilns, they have become the predominant firing methods. Some traditional wood-fired kilns have been abandoned and phased out.

However, wood-fired ceramics have recently seen a rise in popularity, becoming a sought-after specialty product. Among them, wood-fired Tea utensils have gained particular favor among tea lovers. Why are wood-fired tea utensils popular? Compared to tea utensils made using other firing methods, what advantages do wood-fired tea utensils offer?

Wood-Fired Tea Utensils

Enhanced Taste: Good at Softening Water

Practically speaking, the greatest advantage of wood-fired tea utensils is their excellent ability to soften water, which significantly improves the taste when Drinking Tea.

Some may find this claim amazing or doubt it, so the best way to experience it is firsthand: visit any wood-fired tea utensil store and ask the shopkeeper to brew a pot of tea, then pour it into an ordinary cup and a wood-fired tea cup. Try to discern any differences in taste. Typically, the tea tastes smoother and more mellow when drunk from a wood-fired tea cup.