The body of porcelain
Porcelain is mainly composed of body, glaze, and color. The key to the beauty of porcelain lies in the body. The tire is the body of porcelain, which is called the blank before firing. In Jingdezhen kiln industry, there are names such as making blank (forming), printing blank (shaping), shaping blank (trimming), and digging blank (digging the bottom foot). After firing the blank, it becomes the tire. The tire soil is mainly composed of chemical components such as silicon oxide, aluminum oxide, aluminum oxide, and iron oxide. In addition, it also contains small amounts of calcium (mainly calcium oxide), sodium (mainly sodium oxide), and magnesium (magnesium oxide).
Porcelain body. All ordinary porcelain belongs to the porcelain body. The semen extracted from porcelain powder is clarified and melted into mud to form embryos. The porcelain body is ground into powder and finely ground into embryos. The porcelain body has a clear and crisp sound. The sand base of the porcelain body is exposed without glaze. White is more precious than fine sand, with fine sand as the top.
Mud tire. All light and thin porcelain belongs to the category of clay bodies. The texture of the embryo is light and loose. A type of porcelain formed by the use of clear paste during the Ming and Qing dynasties. The paste based porcelain has a thin and light body, and is mainly made of white glaze prints, blue and white bowls, and printing boxes from the Kangxi and Yongzheng periods.
Cylinder tire. Also known as tile body, it specifically refers to a type of porcelain with coarse and heavy soil, with a rough texture, such as Liao porcelain and black glazed thick body bottles fired in Shanxi and Shaanxi regions. The quality of the cylinder tire is heavy and firm, with a precious and bright sound. Over time, the cylinder tire often has a copper sound, so discerning experts often knock on its sound to know its age.
Stone tire. Any heavy and thick vessel belongs to the stone body rather than real stone, but its quality is heavy and firm, slightly resembling a marble carved object. Kangxi had three colored stone tires.
Iron tire. Iron tire refers specifically to porcelain with high iron content in the soil, such as Song Jianyao rabbit hair cups.
The iron tire is not real iron, and the porcelain is almost black, like iron color. The thickness and weight of the tire are also inconsistent.
Born out. Shengde specifically refers to the Yongle white glazed thin placenta bowl. This type of porcelain is as thin as an eggshell, hence it is also known as an egg curtain. Like enamel peeling off, its thinness reflects the threads of fingers.
The glaze color of porcelain
Glaze is one of the important raw materials for producing porcelain, and early glazes appeared on Shang Dynasty pottery, known as primitive glazes. During the Jin Dynasty, porcelain craftsmen had a relatively mature grasp of the techniques for firing blue glazed porcelain. The firing of green glaze has brought about a fundamental difference between pottery and porcelain.
Glaze is made from materials such as quartz, feldspar, clay, etc. It is a thin layer of glassy material attached to the surface of ceramic bodies and has certain physical and chemical properties similar to glass. The chemical composition includes: silicon oxide, aluminum oxide, iron oxide, potassium oxide, sodium oxide, magnesium oxide, calcium oxide, etc. Calcium (calcium oxide) is a very important factor, and porcelain kilns in different regions use different raw materials, such as using wind tail grass ash in Jingdezhen and clam shell ash in Fengxi, Chaozhou, Guangdong. Glaze can not only increase the mechanical strength and dielectric strength of porcelain, but also prevent the erosion of liquids and gases, and is also an important means of beautifying porcelain. After the Qing glaze of the Two Jin Dynasties, white glaze of the Tang Dynasty, red glaze and black glaze of the Song Dynasty all appeared successively, and a variety of glaze colors were created in the Ming and Qing Dynasties.
Glaze is classified according to the body, including porcelain glaze, pottery glaze, and flint glaze; According to the firing temperature, there are low-temperature glaze, medium temperature glaze, and high-temperature glaze; According to the characteristics of glaze, there are white glaze, colored glaze, crystalline glaze, kiln textured glaze, and cracked glaze. In addition to the above-mentioned glazes, there are also matte glazes, opaque glazes, salt glazes, etc.
The glazes used in modern daily-use ceramic production are divided into lime glaze and feldspar glaze. Lime glaze is made by mixing glaze fruit and gray glaze, while feldspar glaze is mainly composed of quartz, feldspar, marble, kaolin, etc. Adding metal oxides or other chemical components to lime glaze and feldspar glaze can result in various glaze colors. The thickness of the general glaze is only 1% to 3% of the thickness of the body. After being fired in a kiln, it tightly adheres to the porcelain body, making the surface of the porcelain dense, with a soft luster, giving a bright and mirror like feeling.
1、 Color glaze
Color glaze, also known as colored glaze or single color glaze, is a type of porcelain glaze known for its purity, elegance, and minimal artificial carving. Color glaze is used to decorate porcelain by changing the color of glaze water. Usually, the content of various trace elements is adjusted in the glaze, iron, copper, manganese, cobalt and other oxidized metals are added, and then appropriate firing conditions are applied to achieve the purpose of changing the color of glaze. The glaze will appear green, brown, red, blue and other colors. The glaze contains iron, which turns blue after firing; Containing copper, it turns red or green after firing. In addition, glaze colors can also be divided into monochrome glaze, crystalline glaze, patterned glaze, and patterned glaze.
2、 Green glaze
Green glaze is a high-temperature glaze that uses iron as a coloring agent and calcium oxide as the main solubilizer. It is the first color glaze to appear in Chinese porcelain. The so-called "green glaze" does not have a pure green color, but has several colors such as yellow, green, and green, but can always have a slight greenish tint. At the same time, ancient people often collectively referred to the three colors of green, green, and blue as "blue". For example, Xu Zhiheng's "Drinking and Flowing Studio on Porcelain" stated: "When it comes to porcelain, it is still green, and all green and blue are enclosed in green." Liu Zifen also said in "Bamboo Garden Pottery": "One type of blue is often mixed with blue. After the rain clears, the blue of Jun kiln and Yuan kiln is close to blue... Only the green of Qianfeng, Meizi green, and Douqing are pure green ears. The sky is originally blue, sometimes green
3、 Meizi Green Glaze
Plum green glaze is a glaze color of Longquan celadon, created and fired during the Southern Song Dynasty. Its glaze color is rich and green, just like the color of green plum, hence the name Meiziqing. The firing of plum green glaze requires high whiteness for the porcelain body. The glaze adopts lime alkali glaze that is not easy to flow at high temperatures, in order to apply glaze multiple times to increase the thickness of the glaze layer. The glaze is fired at a high temperature of 1250 ℃ -1280 ℃ and in a strong reducing atmosphere, resulting in a high degree of vitrification, strong luster, and slight transparency. The glaze is as lustrous as jade.
4、 Holly glaze
According to the "Jingdezhen Pottery Record" by Lanpu, it was fired in the Eastern Kiln of Bianjing during the Northern Song Dynasty (now Chenliu, Kaifeng, Henan), hence it is called Dongqing Glaze, and some also call it Dongqing or Frozen Green. The Dongqing glaze seen today began in the Yongle period and was later fired in various dynasties. Its characteristics are a shimmering green in the midst of green, with lush greenery. During the Yongle period, Dongqing glazed porcelain had glossy vessels and some were decorated with carved patterns. The glaze layer was plump and had many small bubbles. During the Xuande period, the Dongqing glazed ware had a thicker body, and the uniformity of the glaze was roughly the same as that of the water music period. Most of the glazed surfaces had no orange peel patterns, and most of the glaze layers had no bubbles, with slight variations in glaze color depth. During the reign of Emperor Yongzheng in the Qing Dynasty, the iron content in the glaze and the reducing atmosphere during firing were well controlled. The characteristics were smooth glaze surface and stable color, with bean green as the main color tone.
5、 Xianqing glaze
Bean green glaze is a glaze color derived from green glaze, and is one of the glaze colors in Longquan kiln celadon of the Song Dynasty. The glaze color is greenish with a yellowish tint, and its luster is weaker than that of powder green and plum green. The firing level of the bean green glaze in the Ming Dynasty tended to be stable, and its basic color tone was still mainly green with a hint of yellow, with the blue color being more elegant than before. The Qing Dynasty bean green glaze was more elegant and soft, with light colors as light as lake water, and dark colors that were green with yellowish hues, resulting in a thick glaze surface. During the Qing Dynasty, while firing bean green glaze, various colored decorations were also applied to the glaze. After being fired in the kiln for the second time, the bright decorations appeared more charming against the elegant and soft bean green backdrop. After the mid Qing Dynasty, green glazed porcelain was still decorated with raised patterns on the plain body, with blue and white hooks used to outline the patterns, filled with green glaze, and then fired in kilns. The transparency of green glaze is not as good as that of white glaze, so the blue and white effect of green glaze is not as good as that of green glaze.
6、 Yingqing glaze
The glaze contains less than 1% iron and is fired in a high-temperature reducing flame at around 1200 ℃, achieving a whiteness of 70%. Its texture is firm, pure white, and the fetal bone is light and thin. The glaze color is crystal clear and transparent, between the two colors of blue and white
Between the blue and the white, there is white in the green, and the white is tinged with green, hence it is called "Qingbai". Yingqing glaze is the common name for "blue and white glaze". The term "Yingqing" was first recorded in literature in the book "Tao Ya" written by Wen Jiyuan from 1906 to 1911. Afterwards, Xu Zhiheng also wrote in his book "Yinliu Zhai Shuo Ci": "Plain porcelain is very thin, and those with carved patterns that reflect blue are called shadow blue." From this, it can be seen that the term "shadow blue" was named by later generations based on the characteristics of blue and white porcelain, such as moist glaze, thin body wall, and engraved dark flowers that reflect blue. As the blue and white porcelain of the Song and Yuan dynasties also had the characteristics of shadow blue porcelain, the term "shadow blue" gradually became a specialized term for blue and white porcelain in the ceramic industry since the Song and Yuan dynasties, and the Qing dynasty specifically referred to thin body carved products from the Yongle or Wanli periods of the Ming dynasty. In addition, shadow blue is also called "hidden blue" or "reflecting blue". The 'Green'
7、 Tianqing glaze
Tianqing glaze specifically refers to a glaze color used in the imperial celadon fired by the Ru kiln in Henan during the Song Dynasty. The main component of agate is silicon dioxide, which is also the main component in Ru kiln glaze. It is no different from ordinary quartz sand used as glaze, but agate often contains coloring elements such as iron, which play a role in increasing the special luster of Ru kiln porcelain. According to physical observation, the main characteristics of Ru kiln sky blue glaze are a uniform glaze layer, a moist glaze surface, a thick and shiny juice, and a pile of grease like texture. After being fired with a reducing flame, the glaze color is blue like a clear sky. The glaze reveals crab claw patterns and caviar patterns, and the glaze surface has fish scale like cracks.
8、 Pink blue glaze
Pink green glaze is a glaze color derived from green glaze, presenting a powdery green color like translucent jade. It was created by Longquan kiln in the Southern Song Dynasty and is a type of lime alkali glaze. The main coloring agent is iron oxide, with a small amount of manganese or titanium, and it is glazed on the green body with ash in the body. It is fired in a high-temperature reducing flame at 1180 ℃ to 1230 ℃ in a kiln. Due to the high viscosity of lime alkali glaze at high temperatures, it is not easy to flow glaze at high temperatures, and the glaze layer can be applied thick, resulting in a soft and elegant jade texture in the glaze color. The glaze layer of pink blue glaze contains a large number of small bubbles and unmelted quartz particles, which cause strong scattering of light entering the glaze layer, resulting in a completely different visual effect from ordinary glass glaze in appearance. Many porcelain kilns in the Southern Song Dynasty fired powder blue glaze, and the official kilns under the suburban altar also fired imitations of Longquan powder blue. The powder blue produced in Jingdezhen during the Ming and Qing dynasties is light lake green with a slight shimmering blue, indicating that in addition to iron, there are trace amounts of diamond elements in the glaze.
9、 Piao Se
Piao was originally a light blue silk. The so-called 'ethereal color' refers to the glaze color of celadon that is ethereal. The glaze color of Ou porcelain is ethereal. Its color is light green, with more green components in the light gray green. But due to different heating conditions, the glaze color is also not very consistent, with dark gray green, blue-green, yellow green, and even gray and smoky dark red.
10、 Imitation Longquan glaze
One of the varieties of blue glaze. The Longquan glaze imitated by Yongle in the early Ming Dynasty has a greenish green glaze color, thick enamel, and many small bubbles and sagging phenomena. The glaze layer is uniform, the glass quality of the glaze is strong, the color is heavy, and it has the effect of imitating Song and Yuan Longquan, so it is called "imitation Longquan glaze". The imitation Longquan glaze from Xuande period has no orange peel pattern on the glaze surface, and the glaze is shiny without bubbles
