In Shuiji Town, Jianyang District, Nanping City, Fujian Province, the kiln fire that has burned for thousands of years has never truly gone out. Those black-glazed tea bowls born from the Song Dynasty dragon kilns are now known as "Jianzhan" and have become a shining pearl of China's national intangible cultural heritage. The charm of Jianzhan lies not only in its unpredictable glaze patterns, but also in its millennia-old production techniques that embody the wisdom of ancient craftsmen.

I. Sourcing Clay: The "Iron Body" Code Bestowed by Nature

The story of Jianzhan begins with the land beneath our feet. The local porcelain ore resources in Jianyang are the key to the "iron body" characteristic of Jianzhan. Craftsmen must go deep into the mining areas to select yellow mud, clay and red soil rich in iron oxide, with an iron content of up to 6%-10%, several times that of ordinary ceramic raw materials.

After mining, the porcelain ore undergoes multiple processes such as crushing, elutriation and batching. A huge water-powered trip hammer repeatedly pounds the hard ore under the impact of water, grinding it into fine powder. The ore powder is then poured into an elutriation tank, and after multiple sedimentation and filtration processes, impurities are removed, leaving the purest body clay. At this point, the body clay is dark brown, rough to the touch but with unique toughness.

The body clay also needs to go through a months-long aging period. In a dark and damp warehouse, microorganisms quietly decompose the organic matter in the clay, making it finer and more uniform, and enhancing its plasticity. This is a dialogue with time; only patient waiting can yield the solid and thick body of a Jianzhan.

II. Shaping: Transmitting the Warmth of Handcraftsmanship

The aged body clay comes to life in the hands of craftsmen. The clay-kneading process seems simple, but it is actually a key step in making Jianzhan. Craftsmen use their whole body strength to repeatedly squeeze and slap the clay mass to expel air bubbles and make the clay denser. Only fully kneaded clay can remain stable and not easily deform during the throwing process.

Throwing is the most visually appealing link in Jianzhan production. The craftsman sits in front of the wheel, placing the kneaded clay mass in the center of the rotating disk. As the disk spins rapidly, the craftsman dips their hands in water and gently holds the clay mass. With the dexterous manipulation of their fingers, the originally regular clay mass gradually rises upward, forming a bowl-shaped prototype. At this moment, the craftsman's hands seem to have magic: the thumb slowly presses down from the center to create a hole, then gradually expands outward to adjust the size and curvature of the bowl mouth.

After throwing, trimming is required. The craftsman holds a sharp trimming knife and carefully carves the rotating blank, removing excess clay to make the shape more regular and smooth. The unique shallow foot ring and chamfering techniques of Jianzhan are completed in this link. Trimming not only tests the precision of the craftsman's knife skills, but also requires a deep understanding of the traditional shape of Jianzhan.

III. Glazing: The Mysterious Prelude of Uniform Color Before Entering the Kiln

The glaze of Jianzhan is also sourced from local natural ores, with a higher iron content than the body clay. Craftsmen crush the glaze stone and add auxiliary materials such as plant ash to prepare a unique glaze slurry. Jianzhan uses distinctive glazing methods, usually "dipping glaze" or "swirling glaze".

The craftsman holds the blank, inverts it and immerses it in the glaze slurry. At this point, the glaze slurry naturally flows on the surface of the blank, forming an uneven glaze layer. The outer wall of Jianzhan is usually only half-glazed, with a thinner glaze layer at the rim and a thicker glaze accumulation at the bottom of the inner wall. This glazing method is not an oversight, but to prevent the bottom of the bowl from sticking to the kiln furniture during firing, and it also creates the unique "glaze tear" phenomenon of Jianzhan.After glazing, the Jianzhan blank needs to undergo biscuit firing. In low-temperature kiln fire, the moisture in the blank gradually evaporates, and its strength is further improved, preparing it for subsequent high-temperature firing. At this point, the Jianzhan blank is gray-brown, seemingly plain, but it is quietly accumulating energy, waiting for its passionate collision with the fierce fire.

IV. Firing: Rebirth with Myriad Colors After Leaving the Kiln

Firing is the most critical and uncertain link in the production of Jianzhan. Traditional Jianzhan is fired in dragon kilns, whose long bodies are built along the mountainside, like a giant dragon crouching on the slope. Kiln workers carefully place the biscuit-fired blanks into saggars, and then stack the saggars in the kiln in order.

The firing process of a dragon kiln lasts dozens of hours, and kiln workers must constantly monitor changes in temperature and atmosphere inside the kiln. The firing temperature of Jianzhan needs to reach above 1300°C, at which point the iron elements in the body undergo complex chemical reactions with the components in the glaze. Under the action of reducing flame, iron oxides in the glaze gradually precipitate, forming unique crystalline patterns.

Hare's fur, oil spot, yohen (celestial transformation)... These amazing glaze patterns are not deliberately painted by humans, but miracles naturally nurtured by fire and earth at high temperatures. Each Jianzhan is placed in a different position in the kiln and heated to different degrees, so the final pattern is unique. When the kiln fire goes out and the temperature slowly drops, kiln workers open the kiln door with a mix of anxiety and anticipation—at that moment, a miracle is witnessed.

V. Inheritance: The Contemporary Rebirth of a Millennium-Old Craft

Today, although the firing technique of Jianyao Jianzhan has been included in the national intangible cultural heritage list, the road of inheritance is still full of challenges. Traditional handcrafting is inefficient with an extremely low yield rate; a high-quality Jianzhan often requires multiple failed attempts to produce. At the same time, the increasing scarcity of raw materials and the shortage of professional talents also pose difficulties for the inheritance of this ancient craft.

Thankfully, more and more young people are beginning to pay attention to Jianzhan and engage in its production. On the basis inheriting traditional techniques, they continue to innovate, combining modern technology with traditional craftsmanship. The use of electric kilns and gas kilns has changed the firing method, but it has also made the firing process of Jianzhan more controllable. Some craftsmen also try adding new components to the glaze to create richer and more diverse glaze effects.

Jianzhan, the black-glazed tea bowl that has come down from the Song Dynasty, is re-entering people's lives with a new look. It is not only a practical tea utensil, but also a work of art carrying thousands of years of cultural memory. Behind each Jianzhan are the hard work and wisdom of craftsmen, telling the legendary story of fire and earth. In contemporary society, Jianzhan represents not only an ancient intangible cultural heritage craft, but also a respect for tradition and a persistence in craftsmanship.