Chapter 1032: Perfect opening, natural glaze color
Throughout the ages, porcelain has undergone many changes, especially glazes and glaze colors.
The glaze of the Jun kiln of the Song Dynasty is as thick as a pile of fat; the glaze of the Ding kiln is often stained with tears; the enamel of the bodiless porcelain of the Ming and Qing Dynasties is as thin as an egg, and its color is as bright as jade.
The inner and outer glazes of the Yuan Dynasty cutters are often inconsistent, and often have defects such as kiln cracks, glaze leakage, glaze shrinkage, and flattening;
The mouth, bottom, corners and thin glaze parts of Yongle white glaze vessels often flash white and yellow, while the thick glaze accumulation parts flash light pea green, and the glaze on the surface and inside of the cutter is mostly uniform;
The red glaze of Kangxi Lang kiln has the so-called characteristics of "talking off the tongue, hanging down, and the man does not flow" and "rice soup base".
The various characteristics of porcelain in the past dynasties are all manifestations of unique technology, and many of them are difficult for later generations to imitate.
The porcelain in front of you obviously conforms to the characteristics of the Ru kiln of the Northern Song Dynasty. However, when identifying the glaze, you must also pay attention to the size and density of the bubbles contained in the glaze.
The glaze bubbles of Guan and Ge kilns are as dense as pearls, the glaze of Ru kiln is as sparse as morning stars, and the Xuande glaze has "brown eyes". These are features that are difficult to imitate and are also clues to the era.
The celadon glazes handed down from the official kilns, Ge kilns, and Ru kilns of the Song Dynasty have dense network-like flake patterns.
The reason for its formation is mainly caused by the inconsistent expansion coefficients between the tire glazes.
That is, after the porcelain is fired, it shrinks out of sync after gradually cooling down and coming out of the kiln.
The thick or thin, long or short cracks that appear on the glaze of the one-color glaze porcelain are deliberately made by the kiln workers for beautification.
The glaze with open flakes is a special formula.
Only by figuring out this formula can the opening on the porcelain display the effect the author wants.
Looking at the porcelain in front of him that was very natural and tightly cut, Chen Wenzhe studied it bit by bit.
Appraisal means not letting go of any detail.
No matter how good your imitation is in other areas, as long as there is one mistake, all the advantages can be overthrown.
The glaze layer is like gelatin, and the bubbles inside are like morning stars. All these characteristics match Ru Kiln porcelain!
Not a single flaw was found, which made Chen Wenzhe both happy and worried.
Happily, he might be able to get a piece of Ru kiln porcelain from the Northern Song Dynasty.
What is worrying is that maybe his technology is out of date and he is unable to determine the authenticity of this piece of porcelain!
"We still have to watch the opening film!" His mind was racing, and Chen Wenzhe once again determined his identification ideas.
Even though he really wanted to see what the glaze formula used to open the porcelain pieces looked like, he still held back.
With the porcelain in hand, it can't escape. As long as you carefully study the opening technology of this porcelain and determine that the opening technology of this porcelain can reach the level of Ru kiln porcelain in the Northern Song Dynasty, then it will be fine.
If he is really good, this slice-opening technology will be of great help to him in imitating Ru kiln porcelain.
By that time, the authenticity of this piece of porcelain will not matter.
Therefore, the most important thing is to open the porcelain slices, which is also the most difficult technique for Chen Wenzhe to master.
This is a three-legged azure-glazed brush washer from Ru Kiln of the Song Dynasty. It looks a bit like a three-legged bottle tray because it looks very similar to a brush washer.
It is 4cm high, 18.5cm in diameter, and 16.9cm in length.
The supporting plate has a round mouth, a shallow belly, a flat bottom, and three legs underneath.
The inside and outside are covered with azure glaze, and the glaze surface has fine cracks.
The outer sole is fully glazed and has 5 small burnt nail marks.
Although the shape of the vessel is relatively simple, it has a regular shape and the glaze is light azure, soft and moist.
There is no problem with the overall shape of the vessel, so to identify such a piece of porcelain, you still need to look at other features, such as the most important opening. If there is a problem with the opening, then there is no need to look at other parts.
After careful inspection, Chen Wenzhe discovered that the opening technology of this piece of porcelain is really special.
It is cracking from the glaze layer to the carcass.
This kind of deep opening, called "passing", is naturally formed during the firing process in the kiln.
The shallow cracking is caused by the continued shrinkage of the glaze after leaving the kiln.
Due to the different sizes and different depths of the slices, the exposed parts of the carcass also have different degrees of oxidation or contamination.
Therefore, the large opening is dark gray like iron, so it is called iron wire;
The small open pieces are yellowish brown and look like gold, so they are called gold wire.
"Golden iron wire" refers to these two conditions, which are most obvious on the Ge Kiln utensils and have become a distinctive feature of the times.
The opening patterns on Guan kiln artifacts are different from those on Ge kiln artifacts. The patterns are all deep-seated "over-gang" patterns. The opening texture is larger, and its shape is like the sudden cracking of ice on the river ice in winter.
, layer upon layer of exquisite beauty.
The open patterns on the glaze of Ru porcelain are fine and dense, commonly known as "crab claw patterns".
The opening is classic, no problem at all. Seeing the opening of this piece of porcelain, Chen Wenzhe even felt like he had learned a lesson.
At this time, he had begun to feel a little solemn. Maybe this piece was really a porcelain from Ru Kiln in the Northern Song Dynasty.
Instead of caring about authenticity, Chen Wenzhe began to look at craftsmanship.
So what if it's real or fake? Only if the craftsmanship is high enough can it be of sufficient value to him.
For example, glaze, after applying the glaze, is fired. Only when the final glaze gives people a good look and feel can a piece of porcelain be valuable.
The appearance of glaze, including texture and color.
The texture of glaze generally refers to the warmth and moistness of the glaze surface. Generally, the thicker the glaze layer, the more moist it is.
The glaze thickness of the porcelain in front of me is obviously high, so it is not the thin glaze usually found on celadon from the Northern Song Dynasty.
Most of the porcelains where this happens are from the official kilns of the Southern Song Dynasty.
Of course, the official kiln porcelain of the Southern Song Dynasty also had two kinds of glazes: thick glaze and thin glaze. The thick glaze has the most moist glaze.
Thick-glazed Southern Song Dynasty official kiln porcelain needs to be glazed two or three times or even four or five times. After the first few times of glazing, the glaze must be fired at a low temperature of about 800°C, which is called biscuit firing. The last time is at a high temperature of 1230-1270°C.
Fired into porcelain.
During the excavation of the modern Southern Song Dynasty official kiln site, low-temperature plain-fired furnaces and waste products that were not glazed after low-temperature firing were discovered.
The purpose of multiple glazing is to give the glaze a warm and moist texture like jade and to cover up the dark gray body color.
Some Southern Song Dynasty official kiln porcelain bodies are dark gray in color due to the presence of purple gold soil.
From the perspective of silicate, celadon porcelain has three glazes: grass ash glaze, lime glaze and lime alkali glaze.
The glaze on the original celadon was a grass ash glaze, which was characterized by uneven glaze layer. The celadon glaze from the Eastern Han Dynasty to the Northern Song Dynasty was a lime glaze. The glaze was more uniform than that of the original celadon, but the jade texture was not strong.
The official kilns of the Southern Song Dynasty began to have lime-alkali glaze, and the glaze was as moist as jade.
The main components of glaze are porcelain stone, slurry and glaze ash.
The flux (calcium oxide) in celadon glaze is mainly provided by glaze ash. When blending the glaze, if the amount of glaze ash is reduced, the content of calcium oxide in the glaze will decrease, and the proportion of potassium oxide and sodium oxide will increase relatively.
Potassium and sodium are alkali metal elements, so the glaze with this component is called lime-alkali glaze.
The reduction of calcium element will relatively reduce the amount of flux. During the firing process, the glaze will not easily flow obviously due to full melting, resulting in the phenomenon of piling up on the ring feet. Moreover, the glaze fired in this way has a warm and moist texture.