To study blue and white cobalt materials, especially Sumali green materials, in addition to physical and chemical aspects, there must be internal factors of historical changes and deep structural factors.
And how certain is the internal cause that can be grasped? Can it be reliably distinguished?
This is exactly what the comparative test between kaolin clay and Macang soil could not give a clear answer to.
For example, Macang soil is essentially kaolin clay, and its composition is not much different from today’s kaolin clay.
From the laboratory test alone, no obvious difference can be seen between the two, but the fetuses produced are different. Can we say that the two are the same thing?
For another example, the hair of Chinese and foreigners may be black or yellow. Judging from laboratory tests, there may not be any obvious difference, but can we say that they are all from the same country?
Furthermore, where is the kiln site where the materials are taken for testing?
Where was it unearthed? What kind of artifact is it based on?
How representative is it? It’s worth pondering.
According to general chemical analysis, this kind of Su material has low manganese content, which is opposite to the high manganese content of domestic materials.
After the material is fired, the glaze layer shows the most unique uniqueness:
The color is rich and bright, with a hint of purple, and the coarse grains are very distinctive.
The phenomenon of condensed spots, halos, scattering and flow is unique.
The phenomenon of agglomeration spots is much more important than the phenomenon of crystal spots (iron spots). Crystal spots may not be present, but agglomeration spots cannot be eliminated.
The so-called agglomeration spots are black spots formed by the accumulation of pigment pigments during the firing process, which are distributed in the blue pattern.
These black spots are composed of smaller bead-like black spots like millet grains.
And extend in a certain direction in a string or diffuse and gather randomly, or extend into strips, or form larger round spots.
And because these bead-shaped small black spots are dizzy or divergent around them, or have a dripping phenomenon.
Its dizziness is like dizziness, its dispersion is like diffuseness, and its flow is like flowing. It is called dizziness, dispersion, and flow phenomena.
Bead-like black dots strung into strips are called stripe dispersion, and round spots are called patchy dispersion.
Some are scattered, and even the bottom edge of the pattern forms a jagged or ice-hanging state.
There is also a special phenomenon, that is, there is a feeling of swelling toward the surface of the glaze.
That is, the diffusion formed by condensed spots floats to the upper part of the glaze layer, that is, the black spots float upward, while the light blue remains at the bottom.
Suma Liqing materials are scarce and valuable, and it is normal and common for most non-fine or general products to be mixed with domestic materials.
Of course, this will also make the suma leave the green material, reduce the blue or purple color, and turn to a black or gray-black tone. At this time, attention should be paid to distinguishing it from purely domestic materials.
In addition to Su materials, what specific types of pigments were used in the Yuan Dynasty?
In the Yuan Dynasty, domestic materials were also used, because only fine porcelain would use imported suma-liqing materials.
At that time, there were already Shiziqing and Pingpingqing in use in China.
These materials are often used more often at kiln entrances in certain places.
In addition, Huiqing material was also used from the Western Regions of the Yuan Dynasty at that time, and it is also regarded as an imported material today.
The characteristics of these utensils made of domestic materials and recycled materials are more complex.
Domestic materials do not work well when used alone. The phenomenon of agglomeration and beading is atypical, and the color is black, gray, blue and sometimes slightly green.
The black, gray, and blue domestic materials are completely different from the black, gray, and blue materials produced by Suma Liqing due to poor firing.
Even if the su material is not fired well and becomes gray and black, there are particularly obvious bead-like agglomeration spots in it.
However, pure domestic materials, black, gray and blue, lack this beading phenomenon.
It is especially important to clarify here that the black ash of two different materials should not be regarded as the black ash of domestic materials due to poor firing.
This will cause errors in machine inspection and sampling, and may lead to imported materials.
The green material is scattered but not gathered, and the blue color is thicker, slightly purple or showing the color of su material.
But its characteristic of being scattered but not collected is exactly the opposite of Su material.
It only has thick black areas without spots, and is divergent, without bead-like combinations, and the particles are not as thick as Suboni green material. These conditions need to be controlled separately.
The above-mentioned pigments, Suma Li Qing, disappeared after Xuande in the Ming Dynasty, and the rest were used up successively in the Qing Dynasty, becoming the only one.
In modern times, the above-mentioned pigments cannot be imitated, and modern pigments have become extremely fine. After burning, they do not have the bead-like agglomeration spots and dispersion that existed in the natural state during the Yuan Dynasty.
The characteristics of pigments are the most important factor in distinguishing between true and false. If you don’t understand the pigments, you won’t be able to start.
If you see through the paint on an object, the rest will fall into place.
If the paint is not right, it will be useless no matter how good the shape is.
In the past, due to the limitations of the times, it would have been difficult to find the extinct Su Ma Liqing.
However, now is the era of the global village. Is it really difficult to find some unique raw materials from abroad?
It’s just a matter of how much you pay. As long as you pay enough, what can’t be found?
Chen Wenzhe knew that some domestic masters had found raw materials for firing various ancient porcelains, and they all "sourced local materials" at the kiln entrance based on the characteristics of each kiln entrance.
The antique porcelain produced in this way can be said to completely adopt retro technology. If we still can't produce perfect antique porcelain, what's the point of justice?
Of course, firing Yuan blue and white is not that simple, because in addition to pigments and craftsmanship, there is also tire soil and carcass craftsmanship.
Because these characteristics in Yuan blue and white are unique.
Legend has it that the Macang soil produced in Macang Mountain near Shijing Town in the Yuan Dynasty was used to make Yuan blue and white porcelain bodies.
Now Chen Wenzhe thinks that this is a legend. Because the Yuan blue and white production process was kept secret at that time, few people knew what was going on.
Until now, we can only rely on legends to analyze the production technology of Yuan blue and white.
However, the characteristics of Macang soil are still very clear.
After this kind of clay is fired, it becomes crystal clear, warm and soft, and feels slightly smooth to the touch.
It is completely different from modern kaolin fired clay.
This object was very precious in the Yuan Dynasty and was used by the royal family as tribute.
This is the same regardless of the period.
For example, when Ru kiln porcelain is fired, who can tell clearly how to put agate into glaze and how to put agate into glaze?
There is also a secret color glaze, which is called secret color. Naturally, it does a good job of keeping information secret.
The craftsmanship of Yuan blue and white is kept secret, there is nothing to say.
However, Macang soil was very precious in the Yuan Dynasty, which is highly questionable.
Because the Macang soil is dug out from Macang Mountain, can the minerals that can be mined be said to be precious?
Besides, mining of Macang soil is not that difficult, and there is no need to dig under deep wells. Not only is it dangerous, but it is also very costly.
At that time, manual mining was used, so the Macang soil was not considered a precious treasure among the Yuan royal family.
If the quantity is said to be scarce, that would make sense. However, Macang soil was not fully mined until the Ming Dynasty, which shows that the reserves were still very large in the Yuan Dynasty.
So, why was it so valuable in the Yuan Dynasty? It was even listed as tribute soil?
The only possibility is that it is more troublesome to process later, and there is even very little usable soil after processing.
This can be known from the use of Macang soil in the Yuan Dynasty.