The process of firing, building a kiln and building a lamp is actually similar, but the final firing results are different.
Human beings naturally pursue beauty, and sometimes failure is not a bad thing.
Just like firing silver rabbit hairs, sometimes you fail and you get gold rabbit hairs, and sometimes you really fail.
Such a failed product was a kind of gray rabbit hair. During the firing process, the ferric oxide in the iron-rich liquid phase in the glaze had no time to precipitate for some reason, and a large number of anorthite crystals were exposed on the glaze surface.
Anorthite crystals have very low iron content and no reflection. They appear gray or light green to the naked eye, forming gray hairs.
If it is light green, it is the so-called green rabbit hair, otherwise it is gray rabbit hair.
Of course, if your skills are good enough, in the final cooling stage, the glaze can be accurately controlled during the cooling process. When the environmental conditions are suitable and the temperature is suitable when the iron oxide crystallizes, a blue-silver luster can be formed.
This is Blue Silver Rabbit Hair, or Blue Rabbit Hair.
In this way, all rabbit hair lamps can be fired.
However, in this process, gray rabbit hair is the most likely to appear, followed by green rabbit hair, then red rabbit hair, gold rabbit hair, the most difficult is silver rabbit hair, and the most precious is blue rabbit hair.
Firing these various rabbit-hair lamps seems very simple, but when it comes to actual firing, the quality of the work often changes in just a few seconds. If you want to accurately grasp it, you can directly fire the most precious and difficult-to-fire pieces in one go.
It is still difficult to obtain high-quality rabbit hair.
All of this is controlled by temperature. Whether it is the temperature control in the kiln or the glaze temperature during cooling, it is the key.
Why it is said that it is difficult to bake exquisite jianzhan? It is because the time for these key points is too short. Often, if there is a slight negligence or delay, the work in the kiln will turn into another color.
Everyone knows that Jianzhan patterns are naturally formed in a strong reducing atmosphere after being fired at a high temperature of more than 1,300 degrees.
However, as the atmosphere and temperature in the kiln change, the patterns will also change, coming and going erratically and difficult to control.
The firing process is not just about mastering the temperature and atmosphere to produce a good pottery, it really also requires a bit of luck.
If there is a slight deviation, it will be difficult to burn rabbit hairs of better quality, let alone silver rabbit hairs.
After firing several kilns, Chen Wenzhe was able to grasp the key points.
Jianzhan firing, no matter what the final result is, is actually affected by the four major constraints of the blank, glaze, temperature, and reducing atmosphere.
Silver rabbit hair is also seriously restricted by these four factors. The first is the restriction of the blank.
The body must be made from local clay in Jianyang. This clay contains high iron content and is prone to deformation, blistering and other defects at high temperatures.
The chemical and mineral composition of the green body has a significant impact on the glaze patterns.
During the Southern Song Dynasty, other kilns in Fujian Province had poor results, which was directly related to the low iron content in the billet.
Then there are the constraints of the glaze. The thickness of the glaze applied to the lamp is required for the glaze color.
If the glaze layer is thin, the glaze will not be black; furthermore, if the glaze layer is thin, the rabbit hair markings will be short and not smooth.
The thickness of the glaze shrinks greatly during drying, which can easily cause the glaze layer to crack and not adhere tightly to the base. The glaze can easily shrink or deglaze during firing.
The thickness of the glaze has great fluidity at high temperatures, making the glaze layer gradually thicker from top to bottom. The thickness of the glaze layer is uneven from top to bottom, which has a great impact on the formation of markings;
In addition, it is highly fluid and can easily cause sticking to the bottom.
Next is the restriction of temperature. The firing temperature of rabbit hair is high and the range is narrow.
A piece of silver rabbit hair with smooth and smooth markings and flawless appearance has a narrower firing temperature range.
The kiln temperature is slightly lower, and there are markings on the upper part of the bowl but no markings on the lower part.
When the kiln temperature is slightly higher, the glaze will flow down and stick to the bottom.
Finally, there is the restriction of reducing atmosphere. Jianzhan glaze belongs to iron-based crystalline glaze, and the crystallized material is iron oxide.
There are ferrous iron and ferric iron in iron oxide, and the reduction of ferrous iron turns ferrous iron into ferrous iron.
Ferrous iron is a strong flux and easily melts back into the glaze, making the crystalline material unstable and directly affecting the shape and color of the markings.
The substance that creates the color of streaks is iron or iron oxide.
The substances that develop color in an oxidizing atmosphere are mainly ferric oxide, which appears yellow, brown, etc.;
The substances that develop color in reducing atmosphere are iron and iron oxide, and the corresponding colors are silver and blue.
Therefore, when firing silver rabbit hair, it must be produced under reducing atmosphere conditions. Of course, under this atmosphere, blue rabbit hair can also be produced.
Burning silver rabbit hair must be severely restricted by the reducing atmosphere.
In the early stage of firing, it is necessary to restore the original control pattern shape so that it can form filamentous stripes just right;
In the later stage of firing, it still needs to be restored to control the color of the markings. At this time, if the ferric iron is too high, the markings will appear gray.
If the ferrous iron content is too high, the markings will fade or even disappear.
Therefore, the burnt silver rabbit hair markings are not only very unstable in color, but also endanger the shape of the markings, affecting the slenderness, thickness, and border clarity of the markings and many other issues.
There are too many uncontrollable factors in Jianzhan burning, and the range of each factor is extremely narrow.
Ancient kiln workers could only exchange a huge number of kilns and sacrifice a large number of finished products in exchange for one or two excellent pieces of jianzhan.
Therefore, an excellent silver rabbit hair is extremely rare!
This shows the scarcity and preciousness of silver rabbit hair!
On this basis, the blue rabbit hairs accidentally obtained are of course even more rare, so there is a saying that "blue is rare".
At this point, after firing all the rabbit-hair and drip-glaze lamps in all colors, Chen Wenzhe is about to bake the obsidian lamp.
Tianmu glaze is a special member of the porcelain family, and Yaobian Tianmu is the most precious variety.
The firing of Yaobian Tianmu is extremely random. The flare under the glaze fired at high temperature will shine out with colorful halos under sunlight and certain temperature conditions.
This gold, silver, red, cyan, blue, there are several more colors. Needless to say, it will definitely be more difficult to bake.
The most important thing is that there are too many uncontrollable factors, and the range of each factor is narrower. Therefore, it is definitely more difficult to obtain the Yao Transformation Pill than the Tuhao Pill.
Therefore, the Yaobian tea cup is a well-deserved legendary work among the black-glazed tea cups built in the kilns of the Song Dynasty.
Compared with the rabbit-haired lamp, if you want to obtain the obsidian lamp, it means that the decoration inside the lamp should not be distributed in a radioactive manner, but should form spots.
Yaobian is simpler and easier to understand. It means that on the black base glaze, there are many irregular, round or nearly round spots of different sizes.
The distribution of spots in the obsidian calyx is not uniform and there are no rules.
Several or dozens of these spots gather together, and when illuminated by light, they emit a rainbow-like light. This is a unique product of kiln construction.
As for how it feels to the touch, few people can come into contact with a national treasure-level jianzhan, but some people have touched a modern master-level obsidian lamp.
The surface of that kind of obsidian lamp is not as clear-cut as it looks, but is actually flat.
Therefore, if Chen Wenzhe wants to learn how to make Yaobian lamps, he has really waited for the right time.