Ancient sintering process, how was glass made in ancient times?

Glass is the most common and ordinary material in the daily life of modern people, so most people think that glass, like plastic, is a cheap and ordinary thing invented and manufactured in modern times. In fact, there were glass products in 2500 BC. According to archaeological excavations, the earliest ancient glass appeared on the Euphrates and Tigris rivers, in Mesopotamia.

After the 10th century BC, Ancient Greece and Rome also became centers for the development of glass technology. Later, glass-making technology was spread to the Mediterranean coast and neighboring countries.

So, when did ancient Chinese glass products originate? If you want to trace the origin of ancient Chinese glass, it is indeed a long history of development.

1, On the origin of ancient Chinese glass

According to the documents, the cultural exchanges between China and the West began in the 2nd century B.C.E. Therefore, many scholars and Western scholars had believed that the glass or glass-making technology in ancient China was ? introduced from the West after Zhang Qian in the Western Han Dynasty? In fact, during the Western Zhou Dynasty, our ancient ancestors had already mastered glass-making technology.

We know that glass is an indeterminate solid melt. In ancient times, it was mainly composed of quartz (the main component of quartz is silicon dioxide) and some minerals, such as galena (the main component is lead sulfide) or alkaline salts (such as potassium and sodium), which belonged to the silicate system, similar to pottery and porcelain.

From the Neolithic to the ? Yangshao culture? period, pottery developed into colored pottery, which can be described as ? glaze? The germ of the. The Shang Dynasty saw the emergence of glazes. For example, in 1965, Zhengzhou, Henan Province, unearthed a green glaze, engraved with the Shang Dynasty Zun. The mouth and shoulders were coated with a thin glaze, and there were five pieces of dark green thick transparent vitreous glaze. According to archaeological records, the firing temperature of Shang Dynasty blue glaze reached 1,100-1,200°C with fire-resistant crucibles. During the Western Zhou and Eastern Zhou periods, the furnace temperature was higher. The glaze droplets formed at high temperatures during the firing of the blue and white glaze is precisely potassium calcium silicate. This glaze droplet is already a glassy substance and may be the earliest ancient glass in China.

Because the manufacturing process of porcelain glaze and glass is more or less the same, the only difference is that when melting the glass, a container refractory crucible is needed. Therefore, it can be inferred that the earliest glass-making techniques in ancient China evolved from the celadon glaze process.

According to archaeological data, glass artifacts have been unearthed in most of China's provinces and regions, dating from the Western Zhou to the Ming and Qing dynasties. In order to trace the origins of glass in the Han Dynasty, we have compiled a list of the origins of glass in the Han Dynasty.

According to the above table, glass artifacts unearthed prior to the Han Dynasty, some of which are called ? ware? and some are called ? Liuli? Here we would like to clarify that the unearthed opaque and less smooth glass jewelry is known in the archaeological world as ? Artifacts? , while translucent glass beads, tubes, and walls, and glazed pottery used to decorate buildings is called ? glaze? , because those excavated transparent similar to modern production of glassware called glass.

Based on the time sequence of unearthed glassware and the characteristics of the unearthed glassware, we can see that the glass went through the process from the initial opaque and low-luster wares to the semi-transparent glass ornaments and finally to the transparent glassware. In fact, this reflects the development process of ancient Chinese glass technology and ancient science and technology

2. On the Development of Ancient Chinese Glass

The glass production technology is closely related to the glass production technology.

The main raw material for glass making in ancient times was quartz, and the melting point of quartz sand was 1750℃, which could not be reached in ancient times. However, due to the high level of metallurgical technology in ancient China. For example, in the Shang Dynasty, our ancestors already knew how to use the melting agent. They added lead or tin, or both lead and tin to lower the melting point of copper, which reduced the melting point of copper from 1100℃ to 800℃. At the same time, the hardness of copper was increased. As a result, Yin and Shang ancestors were able to produce many exquisite and differently shaped bronze vessels, making them complex bronzes with slender and well-proportioned forms and huge shapes.

So in the manufacture of glass in the process, the ancestors also in the raw material to add grass ash, lead oxide and saltpeter and other fluxes to reduce the melting point of quartz sand:

such as Bozhou, Anhui Province, unearthed at the end of the Spring and Autumn Period and the beginning of the early Warring States period of the semi-transparent beads, scientific testing and analysis, is the earliest discovery of the lead and barium silicate glass;

And Changsha, Hunan Province, Zixing belongs to the Eastern Zhou Dynasty, the excavated tombs of glazed glass, the first time in the past few years, the first time in the past three years, the first time in the past two decades. Tomb unearthed glazed wall, its chemical composition is also lead-barium silicate glass system;

According to statistics, there are more than 100 tombs have been unearthed with Chinese characteristics of the glass wall, beads, seals, sword tube and so on more than 200 pieces, it can be said that, in the middle of the warring states, china has established a lead-barium silicate glass industry. For example, in 1965 in hubei province jiangling Wangshan 1 chu tomb unearthed in the king of yueyang guojian sword grid inlaid with 2 small blue glass, is China's oldest surviving glass.

And China's earliest surviving glass artifacts are the most common is an inlaid glass beads, such as in 1976 in the famous Hubei Suizhou Zenghouyi belongs to the late Spring and Autumn period of a tomb was unearthed more than 100 inlaid glass beads, because in the monochromatic beads embedded in a number of other different from the mother of the topic of the color of the glass, the glass embedded in the formation of a number of concentric circles, at first glance similar to the eyes of animals, so also known as the ? eyes, so it is also known as ? Dragonfly eyes. This inlaid glass beads are extremely complex, the entire process of handmade, not only exquisite and beautiful, but also at that time is also very valuable, rare items.

Liu An, the king of Huainan, the royal family of the Western Han Dynasty, mentioned it many times in "Huainanzi. Tuanhexun" mentioned many times that ? The pearl of Suihou?

Like the bead of Suihou, the jade of Heshi, the one who gets it is expensive, and the one who loses it is poor?

And to the Han Dynasty, glass manufacturing technology has reached a fairly high level, there are many unique glass products. Such as Guangzhou in the early years of the Western Han Dynasty, Nan Yue Wang tomb unearthed 11 pairs of card decorations, are gilt copper frame blue plate glass, glass thickness, color and lustre of crystal, translucent as a mirror, which contains very few air bubbles. After scientific testing and analysis, these blue glass is domestic lead barium silicate glass. Of course, this is not really flat glass, but this has a superior glass production process, for later generations of glass manufacturing has laid a solid foundation for development.

See, China's glass manufacturing technology is not since? Zhangqian through the Western Regions? After the import from abroad, but sprouted in the Western Zhou period, and in the Spring and Autumn and Warring States period has been a large development, the pioneers used in the bronze production technology and alchemy in the use of lead oxide as a flux to make a unique local characteristics of the real glass? Lead-barium silicate glass.

Later, potassium silicate glass was formed by using saltpeter as a flux, and these two types of glass were developed to the Han Dynasty, when the production process was already quite advanced. And spread out to the Korean Peninsula, Japan, Southeast Asia and Central Asia.