It is not easy to reveal the secret of color glaze, especially some of the top glaze colors, how can it be so easy to fire?
After the founding of the Republic, it took more than 50 years to develop more than 40 color glazes.
Langhong is a very famous color glaze.
But “if you want to be poor,
"Shao Lang Hong" is really not for nothing.
Just this popular saying vividly illustrates the difficulty of making Langhong.
"To make Langhong, you must be prepared to lose your fortune."
Chen Wenzhe has fired Lang Hong before, so he knows the difficulty of cooking Lang Hong very well.
This time, Langhong porcelain is mentioned again, mainly because Langhong is related to the firing process of Liuxia lamp.
They are all copper-red glazes, both are high-temperature colored glazes, and their firing process is
The most important thing is temperature control.
Because the temperature of traditional kilns is not easy to control, and predecessors did not have enough grasp of the laws of kiln changes, the failure rate of firing Langhong is extremely high.
Master Deng Xiping discovered through long-term scientific research and repeated experiments that the appearance of Langhong color has a temperature range of 5 degrees Celsius.
If the kiln temperature is higher or lower than this range, it will fail.
Later, by improving the formula and other methods, he expanded this temperature range to 80 degrees Celsius, which greatly reduced the difficulty of firing.
However, the difficulty in firing Langhong is not only the glaze formula and temperature.
Processes such as drawing, glazing, and firing are also very critical. If you are not careful, defects will appear.
As mentioned before, Master Deng has overcome many difficulties in red firing of Lang Kiln, making it easier to bake Lang Kiln.
However, what is easy here is that it is easier to succeed in firing the copper red glaze.
But not all copper-red glaze works are fired just by controlling the temperature.
For example, when it came to making BMWs, it was Master Deng Xiping who tried many times when he made Lang Hong's BMW, but the finished product still looked shaky.
Finally, it was discovered that the problem was with the horse's head, because the statue was top-heavy and its center of gravity was unstable.
Under high temperatures, deformation will occur.
After making targeted improvements, the sweaty BMW was successfully fired.
The BMW is all deep red, with shiny coat and an unusually powerful horse.
If you look closely, you can see that under the shiny surface, there is a silky texture similar to horse hair, which is really magical.
In fact, just slightly modifying the shape of the BMW can be successfully fired.
However, this is a small device, what if it is a large device?
Not to mention anything else, just a piece of clay can torture you to the point of ecstasy.
very few people know,
It often takes more than half a year to burn a large piece of porcelain that is two to three meters high.
It would not be surprising at all if it takes a year to bake but fails.
Why? Let’s talk about the large-sized pots. Do you think it’s the same as making small-sized pots? You can just pull out a rough outline and then trim it a bit.
That's not the case at all. It's very difficult to make large-scale embryos.
Therefore, Chen Wenzhe originally said that large-scale vessels are not easy to make, and successful firing is even more difficult.
So what exactly is the difficulty? The center of gravity just mentioned counts as one. When firing eggshell pottery stem cups, you need to pay special attention to the center of gravity.
If the center of gravity is unstable, the shape of the vessel will definitely fail to be fired. If heated to a slightly higher temperature, the shape of the vessel will deform, and this is not the most important thing.
There are six basic techniques of pottery, and one of the basic forming methods is called the clay bar construction method.
To put it simply, the clay strip construction method is to use clay strips of uniform thickness to make works of various shapes.
This is one of the oldest pottery making methods. When making porcelain, works made of clay strips have the characteristics of uniform wall thickness and easy firing. Sometimes the natural texture of the clay strips can be retained, making people feel vivid and interesting.
Variety.
When using the mud strip construction method, the thickness of the wall can be determined according to the size of the work.
The wall thickness of the work is large, and the clay strips used are also thick;
If the work is small and the wall is thin, the clay strips used should also be thin.
This is the reason why large pots are often made in this way, because they cannot be drawn out.
The method of constructing the mud strips can be changed. For example, it can be constructed in a circle or in a spiral shape. Some decorative mud strips can also be added to create a special aesthetic feeling.
It's easy to make, just take a piece of mud, shape it into balls of the same size, roll and knead them into mud strips, and pay attention to using both hands evenly.
Next, use a strip of mud to form a snail circle as the base, then use a carving knife to carve out the burrs, and apply mud to the burrs.
Then start rolling the mud strips on the bottom plate. When rolling the mud strips, pay attention to tightening the joints between the mud strips. You can also use tools to smooth the inner wall.
Final touches and firing is complete.
However, the real big thing is, if nothing else, the time it takes to roll the mud strips. You can't roll out a large tank over one meter high in one go, right?
Not to mention other things, just gravity can crush and deform the embryo, not to mention drying it in the shade before firing it.
Therefore, making a large pot is extremely time-consuming, and is usually done slowly from the bottom up.
Only when the bottom part has dried a bit and is hard enough to support the weight of the top part can you continue.
In this way, the clay strips are laid out one after another, and finally the embryo is completed. It can only be fired in the kiln after all the subsequent complicated processes are completed.
However, when you open the kiln and check the firing conditions, you often see failed products.
Glaze flow, glaze change, and poor color development are all minor problems.
The big problem is that it will crack directly. The worst case scenario is that it will burn down directly. The entire shape of the vessel will collapse and be completely destroyed.
Why? It’s because of the mud strips and there was a problem when making mud tires.
Dry and wet problems, density problems, heating problems, etc., etc., if any problem is not handled properly, the final result will be firing failure.
Think about it, it took half a year, or even a year, to finally complete the firing, but when you open the kiln and take a look, what you see is indeed a deformed porcelain that cannot be seen at all. How frustrating it must be at that time
?
Chen Wenzhe's firing success rate actually relies on inherited experience. Without this experience, how could he have such a high success rate in firing porcelain?
Unfortunately, in the course of thousands of years of development, many porcelain-making techniques have been lost.
For example, the "Liu Xia Zhan" of the Ming Dynasty was originally only seen in the poems of the ancients, and no one had ever seen the real thing.
Master Deng Xiping spent 23 years deciphering the craft secrets of Liuxia Zhan.
He was even able to successfully develop the "secret glaze Liuxia lamp" by combining it with the secret porcelain craftsmanship of the Tang Dynasty.
Such a work, the colors are like flowing clouds, unparalleled beauty!
But if you really want to make a perfect secret-color glaze lamp, how many people know how difficult it is?
Different colors can appear only when glazes prepared from ores from the origin undergo physical and chemical changes at high temperatures to form gemstone structures.
Changes in the composition of the raw ore, changes in the firing process, and even different kiln locations will affect the final color.