Coloured glaze is known as the first of the five famous vessels (gold, silver, jade, coloured glaze, ceramics and bronze) in China, and one of the seven treasures of Buddhism. The Ming dynasty was basically lost. However, even the very incomplete Ming dynasty crafts were still protected by grades, and the colored glass at that time was already very opaque, so it was called medicinal jade. "Ming system" contains: the jewelry given by the emperor to the champion is medicinal jade, which is only for more than four items.
China glass's invention is closely related to bronze smelting technology. Glass usually refers to silicate compounds that are melted, cooled and solidified. Quartz sand is the main raw material for melting glass, and other raw materials include pure sand and limestone. The melting temperature is 1200℃. In the process of smelting bronze, due to the melting of various minerals, glassy substances will appear in the discharged copper slag, which are filamentous or massive silicon compounds. Because some copper particles invade the glass, the vessel appears cobalt blue or cobalt green due to oxidation and reduction at high temperature.
In ancient China, glass was called "Liulin", "Streamer" and "Coloured Glass", and it has also been called "Li Po" since the Southern and Northern Dynasties. According to the records in Guangya and Jijie, for a long time, "glass" was the general name of transparent substances such as glass beads made by fire. Since the Ming and Qing Dynasties, people have called "coloured glaze" opaque, which is of course different from glass. There is an old saying: "Most window sashes are green glazed windows, all of which have light, so you can't hide your hair." . Explain that transparent doors and windows can be completely exposed at that time. There is another cloud: "glazed glass makes it shine through the hole." . It can be seen that the so-called "window bright and clean" is not modern.
Chinese civilization lasted for five thousand years. From the Spring and Autumn Period to the present, colored glaze is closely related to people's lives. The glass screens, glassware, glass bowls recorded in Shi Shuo Xin Yu and the glass clocks mentioned in Jin Shu Cui Hongchuan were also unearthed in the tombs of the Western Zhou Dynasty in Tunxi, Anhui Province and the Spring and Autumn Period and the Warring States Period in Shaoshan, Hunan Province. Bowls, hooks, seals and other glazes are common in Han tombs. A glass wall with a diameter of 234 mm, an aperture of 48 mm, a thickness of 18mm and a net weight of 1.9kg was also unearthed near Maoling, Emperor Wu of the Han Dynasty in Xingping, Shaanxi. A large number of glazed utensils unearthed in the underground palace of Famen Temple in the Tang Dynasty, and 33 relic glass bottles unearthed in Peiji of the Northern Song Dynasty in Dingxian County, Hebei Province, are as thin as paper and as bright as crystal; Polished glass unearthed in Tianchang, Anhui Province, and hundreds of egg-shaped glass bottles unearthed in Mixian County, Henan Province are all evidences of the technological progress of glass manufacturing and the developed level of blown glass in the Northern Song Dynasty. Large-scale production of glass began in the Ming Dynasty, and the palace glass yard was set up in Kangxi in the Qing Dynasty, which has been able to produce transparent glass with more than 15 colors and monochrome opaque glass. Silk-wrapped glass, colored carved glass and snuff bottles in the Qing Dynasty are all treasures of glass art in the world.
There are great differences between Chinese and foreign ancient glassware, mainly because "lead-barium glass" in China and "soda-lime glass" in the west belong to two different glass systems. China ancient glass is mainly composed of lead and barium, which is said to have been accidentally fired by an ancient Taoist alchemist. The firing temperature is low. Although the color is bright and shiny, it is fragile and has poor transparency. It is not suitable for sudden cooling and heating. It is only suitable for processing into various decorations, ritual vessels and funerary objects, and its use is narrow. The glass unearthed in ancient Egypt and the Mediterranean coast is mainly composed of sodium and calcium, which overcomes the weakness of "lead-barium glass" and has high strength. Therefore, the usage and output of this ancient glass is far greater than that of China ancient glass.
It is not easy to preserve ancient glassware, because most ancient glassware are "lead-barium glass", which is fragile, and many of them have been broken or damaged when unearthed. Except for a few unearthed cultural relics, there are not many complete cultural relics circulating among the people, and most of them are preserved in major museums across the country. According to statistics, in recent ten years, there are very few complete over-the-glaze colored wares unearthed in various places, and the market price of ancient over-the-glaze colored products circulated by the people is rising continuously. Some time ago, in the "Jianbao" column of CCTV, a Jianbao person photographed a copy of tortoise shell duck in Qing Dynasty, which was 6.5 cm high and 10 cm long, and the expert estimated it at 8,000 yuan. And foreign countries love glassware far more than China!