In recent years, the Jian Zhan industry has continued to develop, gradually becoming popular in the collector's world. It has been used as a national gift for foreign dignitaries and has repeatedly reached new highs in auction prices at major international auctions, gaining favor from an increasing number of people and becoming the "new favorite" in the collector's world. For many Jian Zhan enthusiasts, identifying the types of Jian Zhan and appreciating the glaze colors is easy, but they are not experts in the firing process of Jian Zhan. What kind of firing process is it, and how many procedures are needed to turn a handful of inconspicuous red-brown clay into exquisite porcelain? How many challenges need to be overcome to be successful?
The firing process of Jian Zhan includes: 1. Selecting clay and minerals 2. Crushing the clay 3. Washing and filtering 4. Aging 5. Kneading and mixing the clay 6. Shaping 7. Trimming 8. Bisque firing 9. Preparing the glaze 10. Applying the glaze 11. Loading the kiln 12. Firing 13. Unloading the kiln. Although these steps seem simple, the craftsmen spend countless days and nights on them, and the hardships are self-evident.
1. Selecting clay and minerals As the saying goes: without iron clay, there is no Jian Zhan. During the Song Dynasty, Jian Zhan stood out among many porcelains and became the favorite tea utensil of Emperor Huizong of Song, with the iron clay playing a decisive role.
Jian Zhan is named after the Jian Kiln, located in Shuiji Town, Fuzhou, Fujian Province. The high iron content in the local red-brown clay makes it the best raw material for firing Jian Zhan. However, not all red clay from the town is suitable for firing Jian Zhan, requiring a series of tests to select the most appropriate clay.
2. Crushing the clay The selected granular red clay is crushed into fine clay using certain tools.
3. Washing and filtering As the name suggests, this step involves sieving and filtering granular objects from the clay, facilitating subsequent processes.
4. Aging Aging, a term in porcelain-making, refers to storing the clay in a closed room without sunlight and air circulation, while maintaining a certain temperature and humidity. Generally, the longer the aging, the better.
The purpose of aging is to make the clay more uniform, enhance the strength and plasticity of the body, and reduce the likelihood of deformation.
5. Kneading and mixing the clay Kneading and mixing the clay removes air and impurities, making the clay finer, more compact, and evenly moist, reducing the chances of drying, cracking, and deformation during shaping.
6. Shaping Shaping involves hand throwing and machine mold pressing. Hand throwing is done by craftsmen manually, usually requiring experienced artisans. Machine mold pressing is more efficient than hand throwing but often results in a uniform look, so it is priced lower than hand throwing.
7. Trimming Traditional Jian Zhan has a shallow ring foot trimmed with a trimming knife. Some artisans, to show their unique style, prefer toothed trimming knives. After trimming the foot, a bottom mark can be added, either hand-carved or stamped.
8. Bisque firing Bisque firing refers to pre-firing the unglazed Jian Zhan body at a low temperature, enhancing mechanical strength and removing some brittle, crack-prone bisques. Despite this, Jian Zhan may still deform or crack during kiln firing.
9. Preparing the glaze The glaze color and patterns of Jian Zhan are mysterious and varied, but its glaze formula is very primitive, made by mixing natural iron glaze minerals with plant ash. Experts have tested and confirmed that the glaze is safe and non-toxic.
10. Applying the glaze Applying a half glaze is a characteristic of the Jian Zhan firing process. If a full glaze is applied, the glaze water will flow downwards at high temperatures, causing sticking to the bottom. The glazing process requires skill; if too thin, there is little room for crystal growth, making it difficult to form exquisite patterns. If too thick, it may stick to the bottom.
11. Loading the kiln Traditional dragon kilns use sagger boxes for loading, while modern electric kilns often pad the bottom with alumina powder.
12. Firing During the Song Dynasty, Jian Zhan was fired in dragon kilns built against mountainsides. Today, artisans mostly use electric kilns for firing Jian Zhan. Regardless of the firing method, two conditions must be met: maintaining a high-temperature environment and a good reduction atmosphere in the kiln. To fire fine Jian Zhan, both are indispensable.
After loading the Jian Zhan into the kiln, the firing master must focus entirely and carefully control the temperature inside the kiln, imagining the hardship of ancient dragon kiln craftsmen. Firing in an electric kiln today is not as simple as flipping a switch; the electric kiln itself cannot automatically create a reduction atmosphere and must be manually controlled.
13. Unloading the kiln Due to the difficulty of the Jian Zhan firing process and the low yield rate, some defective and substandard products inevitably appear and are usually disposed of on-site, not entering the market. "One color enters the kiln, thousands emerge"; the fine Jian Zhan pieces that come out of the kiln are unique, products of the right time, place, and people, world-class treasures, and a blessing from the heavens.
The firing process of Jian Zhan can be described in simple words, but the hardships involved are indescribable. During the firing process, craftsmen also need to make timely adjustments based on changes in time, climate, and temperature, facing a variety of challenges, enduring hardships, all for one Jian Zhan.