Knowledge Series of Blue and White Porcelain: Understanding Fetal Glaze
embryo glaze of blue-and-white porcelain
1. Several common characteristics of blue-and-white porcelain tyres in the current market
At present, the market for blue-and-white glaze materials, the common white mud, high white mud, ultra white mud, antique mud.In essence, jade mud is not suitable for firing blue and white flowers, the specific reasons below will be analyzed, but there is also a real market with jade clay made of blue and white porcelain, so here is also listed to talk about.Hand-panned mud and old mud will be used only if they are made to imitate old ones. It is not easy to see in the market. The root cause is that these two kinds of clay materials not only have low fault-tolerant rate, but also less scarce materials, so they are not always used as daily appliances.
White mud: Let’s give an example of a physical object for a more intuitive understanding, and our own series of knife-and-word patterns is white mud.It is characterized by the relatively white clay, but the color is not white white white, compared with the old clay white will be higher.It is highly malleable and generally does not burn out the porcelain.Another of its porcelain is not particularly hard. At present, most of its porcelain is made of white mud
High white mud: this kind of clay is white as its name implies, the advantage is obvious, it is white so that you can hardly see any impurities, with modern feldspar glaze (blue and white glaze) fired porcelain is basically no flaws, in line with the modern people’s aesthetic.Its mud is very expensive, high white mud clay now about 18000-20000 yuan a ton.It is mainly produced by Delta.Delta collects high-quality kaolin from all over the country and then refines the tire mud used in porcelain by modern processes.At present, most of Jingdezhen porcelain, we see that there is no impurities in the white, basically all made of Daidaogao white mud or ultra-white mud.When high and ultra-white mud made of two cups together, it is clear that the ultra-white mud will be more white.
Jade mud: The clay cost is very high.At present, there are two kinds of jade mud on the market: one is what we call jade mud, the other is sheep-fat jade mud.Shea fat jade mud than ordinary jade mud more expensive, about 30,000 yuan a ton.This kind of jade mud material looks at the base of the finished product easy to distinguish, although it is called jade mud, actually its agate feeling is more prominent.Essentially, it is only suitable for burning oxide flame, this kind of clay is very suitable for burning white porcelain, such as the white porcelain of burning Dehua is very good, of course, because Dehua porcelain is mostly machine rolling billet, the body is thicker, the body temperature resistance will be much higher, thick billet can burn to 1300-1330 degrees;But Jingdezhen do the billet is relatively thin, basically can only burn to 1260 degrees, and blue and white to reach 1290 degrees can hair color, temperature does not reach, blue and white hair color will turn gray black, in principle, is not suitable for burning blue and white.Whether it is jade mud or sheep fat jade mud, Jingdezhen mostly only use it to burn the white tire, and then paint powder or enamel color, because the clay clean white, smooth texture, can better foil the colorful porcelain beautiful hair color.
Antiquated mud (also known as old mud): First of all, we want to have a recognition that the antiquated mud certainly does not refer to a certain kind of clay, as the name implies, imitation of “ancient” mud, is to imitate the ancient times of a certain generation of mud characteristics, according to the formula of the mud to imitate, this we call antiquated mud.There are many kinds of imitation ancient mud, imitation Qing (imitation Qing three generations, imitation Guangxu, etc.);Imitating the Republic of China;There are several kinds of imitating Ming Dynasty, such as Yongxuan Period, Chenghua Period, Jiajing Wanli Period, etc.There is also the imitation of the Yuan Dynasty.The mud characteristics of each era are different, the relatively white imitation, the relatively yellow imitation, not only hair color and the bottom of the foot glaze joint firing effect is not the same.
As for the cost of antique mud, in general, the price of a ton of antique mud is lower than that of high white mud, ultra white mud, jade mud, sheep fat mud.Because antiquated mud does not require the full use of modern tools to remove all impurities, the relative cost will be lower.As far as I know, according to the degree of imitation, most of Jingdezhen’s ancient mud in 1000-3000 yuan a ton.The imitation is more expensive, and the imitation is about 1500 yuan a ton, which accounts for a very low proportion of the cost of making porcelain.
Hand-scoured mud: so-called hand-scoured mud, that is, according to the ancient law through hand-washed mud, short for hand-scoured mud, it is not a particular kind of.The clay mentioned above is produced by modern processes, such as ball mills and raymongers, with relatively low labor costs.The biggest difference between hand-scoured mud and modern craft clay is that the finished products produced by hand-scoured mud show different textures.For example, we use Jingdezhen kaolin, porcelain stone is also Qimen or Jingdezhen surrounding porcelain stone, while the ancient clay on the market is basically used in Fujian and Zhejiang kaolin, in the mineral composition has been slightly different.
Old mud: Ancient times of war, war is the use of taxes and corvee military service pile out, people can’t plant land, home can’t go back, if we catch up with natural disasters, basically a dead end.In such a period, the Chinese porcelain production of these industries naturally stopped, the clay training ground is also naturally abandoned.For these useless china soil, can not eat and no other use, but also worthless, directly buried in the ground abandoned.By the time of rebuilding in the 1980s and 1990s, a lot of old porcelain clay had been found in Qimen. (Many of the porcelain stone clay in Jingdezhen came from Qimen, which has been recorded in history.)Antique porcelain makers used the clay to make a trial firing and found it to be very similar to some dynasty porcelain.This is the origin of the old mud.Of course, the range of old mud is also very wide, by no means simply refers to a certain kind.Some are near Kangxi, some are near Yongzheng, and some are near Yongsheng.These china clay are used to make top antiques.
Second, the history of the change of celadon glaze medicine in Jingdezhen
Jingdezhen blue-and-white porcelain glaze changes, is always in progress.It can be said that Jingdezhen kiln fire for many years, the craftsmen on the glaze of the exploration and experiment on how many years, it is a cumbersome and quiet process.In the long 1000 years nearly 2000 years of firewood kiln firing process, after numerous test adjustment, in the tire glaze research area has accumulated a lot of experience, which kind of glaze most suitable blue and white hair color, the ratio of the embryo glaze how to be more appropriate, perhaps can not produce any concrete chemical ratio equation, But the practice proves that it is scientific.We do not have to follow the ancient law, but we must inherit the good things, inheritance.
The traditional lime glaze of Jingdezhen has been proved to be the best choice for blue-and-white porcelain in the process of kilns burning for thousands of years.The reducing atmosphere in the firing process of firewood kiln is beneficial to the hair color of the traditional lime glaze, the iron content of the traditional lime glaze is higher, and the finished product is green in white, which not only helps to set off the hair color of the blue and white flowers, but also changes the color in different light, making the object look like “living”.
The big change of glaze medicine comes from the change of kiln and firing method.
With the change of the times, from 1956, the firewood kiln in Jingdezhen began to be abandoned gradually.Only the firework kilns of Jianguo Porcelain Factory were still burning, while the other kilns were gradually converted into coal kilns or tunnel kilns, and gas kilns appeared in the 1990s.
The traditional lime glaze, which is most suitable for burning of firewood kiln, can’t adapt to the new kiln and firing mode.As mentioned above, the reduction atmosphere in the firing process of the kiln is favorable for the color of the traditional lime glaze, which is due to the strict control of carbon monoxide in the kiln, if the content of carbon monoxide is too high, it will lead to smoke yellow porcelain.And coal kilns, heavy oil kilns, gas kilns in the process of burning high carbon monoxide content, with the traditional glaze formula, there will be yellowing, lost the effect of green white.
In this case, Jingdezhen craftsmen and people have carried out many experiments, slowly adjust the formula of glaze, modern feldspar glaze began to board the stage of blue and white porcelain firing, feldspar glaze more adapted to this change after the burning method, its characteristics are white after firing, But it doesn’t change in different light.
Therefore, the present gas kiln fired porcelain, rarely use the traditional lime glaze, because the finished product is not ideal.