The mud required for making porcelain is all transported from the mountains. The price of this material is not high. It is Longquan's natural resource.
The soil brought down from the mountains cannot be used in this way. It must be cleaned.
This cleaning process is nothing more than filtering out impurities.
In order to reduce the iron content, large magnets are used to absorb the granular iron;
The glaze is the natural color of purple gold clay, and now there are very few pure purple gold clays.
Once you have qualified soil and made a qualified embryo, you can start firing it in the kiln for the first time.
Prepare the firewood, light the kiln fire, and smoke will evaporate.
The kiln, which has been built for more than a year, looks like a long dragon from a distance, so the ancient kiln is also called "Dragon Kiln".
It is this kind of firewood kiln that inherits the traditional firing method of Longquan celadon.
The kiln entrance that Chen Wenzhe is using now is a copy of the ancient dragon that he designed.
In ancient times, if the fire inside the kiln mouth was continuous, it could only be fired twice a year.
That’s why the cost of firing ancient wood kilns was so high.
Of course, by the Qing Dynasty, especially in the first year of Xianfeng in the Qing Dynasty, this kind of dragon kiln had been developed very well. The most important thing was that the number of kilns fired at one time was large.
During that period, a dragon kiln could have a face of more than 30 meters, be divided into more than 20 chambers, and could burn more than 10,000 pieces at a time.
After the kaolin is crushed and washed, it is clay-molded and shaped. It then goes through multiple processes such as trimming, decoration, biscuit firing, and glazing before it can be placed in a sagger and installed in the kiln.
In the dragon kiln, it is burned with firewood for one day and one night and then cooled for three days and three nights before it is completed.
When firing the kiln, the craftsman cannot relax for a moment.
Together with the kiln workers, they must stay on both sides of the dragon kiln day and night, observe the color of the flames, and replenish firewood through the firewood holes on both sides of each chamber.
Until the temperature reaches 1300 degrees Celsius - that is the temperature at which a good celadon glaze color is produced.
Thanks to Longquan’s unique minerals and kaolin, Longquan celadon can be fired with the warm and jade-like feel.
To achieve this, in addition to the raw materials, the control of the heat is even more important.
Especially the temperature, if the temperature is not controlled carefully, it will deform and produce color difference.
Even if you are experienced and squat in front of the kiln all the time, the final yield is still only 1/10.
This is a combination of earth and fire, which is difficult to control manually, so good works are hard to come by.
Of course, despite this, Chen Wenzhe still insists on inheriting the ancient firing techniques.
During the firing process of more than a thousand years, Longquan Kiln formed kiln sites represented by Ge Kiln and Di Kiln.
The black-bodied thick-glazed open-piece porcelain that appeared in the Southern Song Dynasty was produced by Ge Kiln, one of the five famous kilns in the Song Dynasty;
The ones with white body and thick glaze, and those with green and soft glaze color are from Di Kiln.
Among them, pink green and plum green are the representatives of the beauty of traditional celadon glaze colors.
Green as jade, as bright as a mirror, as thin as paper, and as loud as a chime, these are the classic characteristics of the top-grade Longquan celadon.
In Longquan, celadon is both a work of art and a daily necessities.
For thousands of years, the brilliance of celadon vessels has not only been collected in museums and displayed in shops on West Street, but also decorated the coffee tables, dining tables and balconies of ordinary people.
Glaze color is the soul of celadon.
A good glaze formula requires hundreds of trials to succeed.
Therefore, the glaze making recipes of ancient craftsmen were often passed down from master to apprentice and kept secret.
It is much easier for Chen Wenzhe to obtain some good formulas.
For example, regarding the celadon glaze formula, my country established the state-owned Longquan Porcelain Factory and Celadon Research Institute in 1957.
This enabled Longquan celadon production to return to a high level in a very short period of time.
Concentrating your efforts on big things has always been the most effective way to tackle key problems.
Thanks to the efforts of many parties, the nearly lost glaze proportioning method of Longquan celadon was basically restored.
Now every celadon manufacturer has their own different glaze adjustment methods.
Therefore, the glaze color after firing is not exactly the same.
Adjusting the glaze is a secret recipe passed down from ancestors, which is unknown to outsiders.
But it will definitely not be added pigment, because the glaze color is produced in the reducing flame.
In the afternoon, the warm sun shines slantingly.
The semi-finished product that was fired in the kiln yesterday has come out of the kiln.
This is the first step of bisque firing, and the workers skillfully take out the bisque-fired body.
After it cools down, Chen Wenzhe will put the jade body into a glaze bucket with glaze and glaze it.
Dip the green body into the glaze slurry and then take it out so that the glaze slurry evenly adheres to the surface of the green body.
Then the glaze slurry is injected into the body and swirled back and forth so that the glaze slurry covers the inner wall...
After several steps such as glazing, dipping, glazing, and spraying, the glazing is completed.
For thick-glazed celadon, several layers of glaze must be applied, and one layer must be applied once and then fired several times before being fired.
One issue worth paying attention to here is the firing temperature. Longquan celadon needs to be fired twice. The first time is called plastic firing, which can also be said to be plain firing.
That is, the embryo of celadon is fired at a temperature of about 800 degrees and is glazed after it comes out of the kiln.
The second time the finished product is fired, the firing temperature is around 1300 degrees.
Generally, it is a relatively accurate 1300 degrees. If the temperature is a few degrees lower, the glaze color will not be transparent enough, that is, it will not be bright enough.
If the temperature is a few degrees higher, the glaze will flow, and the entire kiln will most likely be defective.
Longquan celadon also has a big flaw, which is that it is easy to deform due to the soil problem.
To control this deformation, the most critical thing is the tires.
If the body is thick, it will crack. What's more, celadon has a unique place among porcelains because of its thin body and thick glaze. However, if it is too thin, it will easily deform.
If these problems are solved, after firing, you still need to look at the glaze color and enamel.
The most classic essence of Longquan celadon is the glaze color, and the highest state is the jade-like glaze but not jade.
In this regard, porcelain craftsmen have been exploring for thousands of years.
Now if we want to regain our glory or even make a breakthrough, technological innovation is essential.
For example, compared with dragon kilns, liquefied gas kilns have the possibility of continuous innovation.
In the 1990s, Jingzhen already had a shuttle kiln burning liquefied gas.
Inspired by this kiln mouth, a new type of manually controlled kiln was transformed.
This kind of kiln can solve the problems of impure and unstable glaze color.
Celadon fired by ancient methods represents the inheritance of thousands of years of skills.
Modern gas kilns make influencing factors more controllable.
Combined with breakthroughs in glaze preparation technology, the resurgence of contemporary celadon can be achieved.
From copper-colored glaze, to high-temperature black glaze, to tiger-spot glaze, and black glaze...
With the help of modern technology, modern celadon product designs and creativity have become increasingly rich.
Standing on the shoulders of these predecessors, Chen Wenzhe will naturally have more choices.
He can get the glaze color he wants without relying on experience and trial and error.
However, if he wants something better, he must make repeated comparisons during the firing process.
Only by revising the formula many times can we achieve a breakthrough in the research on the preparation technology of traditional Longquan celadon glaze.
Finally, the glaze color that has been washed out over the years is recovered, and the pure plum green, pink green, and iron tire Ge kiln celadon are given a new life.