You may not know that there was also glass in ancient China.

"Most beautiful things are not solid, colorful clouds are easily dispersed and glass is brittle." A poem by Bai Juyi vividly points out the fragility of glass.

In ancient China, "liuli" was often used to refer to glass (but the term "liuli" does not refer specifically to glass, some glaze sand, jade wares, and glazed bricks and tiles were also called "liuli" by the ancients). In addition, ancient glass also had other names such as "璆琳琅掕", "琉琳", "药玉", "瓘玉", "哨子" and "料器".

Foundation: Ceramic technology, bronze smelting technology and glaze sand

Unlike crystalline substances such as natural gemstones, glass is an amorphous substance. Its structure is not very stable and it is plastic within a certain temperature range.

Therefore, people have long used silica-containing ores as the main raw material for melting glass, and then added different fluxes (such as nitrate, saltpeter, wood ash, etc.) to lower the melting point, heating it to above 1000°C to melt it into molten glass. During the cooling process, various glassware can be made through different plastic forming methods such as pressing, blowing, and drawing.

In addition, people also add minerals containing transition metal elements such as iron (Fe), copper (Cu), manganese (Mn), and cobalt (Co) to make glass present different colors.

The earliest glass in the world appeared in the Mesopotamian region around the 20th century BC. With new archaeological discoveries and the development of non-destructive analysis technology, the unique glassmaking tradition of ancient China has gradually become known.

A large number of glaze sands unearthed from ancient tombs from the Western Zhou Dynasty to the Spring and Autumn Period can be regarded as the predecessor of ancient Chinese glass. The raw materials and appearance are similar to glass. They are made of fine quartz sand powder as raw material, added with adhesives and fluxes, molded into beads or tubes, and then sintered at low temperature (about 900℃). There is a small amount of glassy material on the surface, and the interior is mainly unmelted sand particles.

my country's long-standing ceramic technology and bronze smelting technology provided the technical conditions for the emergence of glaze sand.

my country was able to produce primitive porcelain with glaze layers during the Shang Dynasty. The production of glaze sand is similar to the firing of ceramics. It adopts the method of forming first and then firing. As long as the temperature is sufficient, glaze sand can be produced. The bronze smelting technology provides technical references for glaze sand production, such as temperature control and tool pressing.

Most of these glaze sand beads and tubes were strung together with jade, agate and other beads and tubes as decorations for the tomb owner. Unlike the early glaze sands in West Asia and Egypt, which contain high Na2O, the ancient Chinese glaze sands contain high K2O, which may be related to the high K2O content in the flux plant ash used in China.

Glaze beads

(Photo source: China Glass Network)

After the Warring States Period, real glass products began to appear in China, and glaze sand products gradually disappeared. In the ancient tombs of the late Spring and Autumn Period and the early Warring States Period, people not only found typical Western sodium-calcium silicate glass (Na2O-CaO-SiO2) - dragonfly eye glass beads produced in ancient West Asia or Egypt, but also found potassium-calcium silicate glass (K2O-CaO-SiO2) unique to ancient China. The glass inlaid on the sword guard of the famous Goujian Sword belongs to potassium-calcium silicate glass.

The Sword of Goujian, King of Yue, inlaid with blue glass

(Image source: History of the Development of Ancient Chinese Glass Technology)

Chinese characteristics: the emergence of lead-barium silicate glass

During the Warring States Period, lead-barium silicate glass (PbO-BaO-SiO2) and potassium silicate glass (K2O-SiO2) developed in the Yangtze River Basin.

Lead-barium silicate glass is currently internationally recognized as the most unique glass system in ancient China. It is a silicate glass with lead oxide (PbO) and barium oxide (BaO) as the main flux. Its main raw materials are quartz sand (the main component is SiO2), galena (the main component is PbS), barite (the main component is BaSO4), saltpeter (the main component is KNO3), etc.

By learning from the bronze production process, people used die-casting and other methods to make various glass objects. Because barium oxide can make glass appear milky white to imitate jade, glass became a substitute for jade to a large extent at that time.

In the middle and late Warring States period, lead-barium silicate glass began to appear in large quantities with the Chu culture area as the production center. Typical lead-barium silicate glass objects include: bi disks, sword ornaments, seals and other small decorations.

Glass wall

(Photo source: China Glass Network)

During the Western Han Dynasty, the production of lead-barium silicate glass continued to develop, and the shapes of the glassware also changed: glass plates, glass ear cups, glass clothing pieces, glass ear pendants and other daily necessities and large practical handicrafts began to appear. The discovery of the glass chime in the Han Tomb of Dayun Mountain in Xuyi, Jiangsu Province indicates that the manufacturing technology of lead-barium silicate glass in my country had reached a fairly high level during the Western Han Dynasty.

Glass Chime

(Image source: History of the Development of Ancient Chinese Glass Technology)

After the Eastern Han Dynasty, the trend of using lead-barium silicate glass to imitate jade was no longer popular, and the chemical composition of glass also changed accordingly. High-lead silicate glass (PbO-SiO2) gradually became the mainstream of China's homemade glass.

Exchanges between China and foreign countries: the introduction of glass blowing technology

During the Wei, Jin, Southern and Northern Dynasties, Roman glass and glassware made by the Sassanid Empire poured in, and glass blowing technology was also introduced. Due to the prevalence of high-lead silicate glass without barium oxide, the transparency and gloss of glass were significantly improved.

Roman glass unearthed from Tomb No. 7 at Xiangshan, Nanjing

(Image source: History of the Development of Ancient Chinese Glass Technology)

During the Sui and Tang Dynasties, the glassmaking technology spread and developed further, and the number of daily utensils such as glass bottles, glass cups, glass bowls and plates increased. At the same time, influenced by Buddhism, glass relic bottles also appeared in large numbers.

Tang Dynasty glass tea bowl and tea tray

(Photo source: China Glass Network)

High-lead silicate glassware made by blowing has also become another ancient glass unique to China. However, since high-lead silicate glass is very corrosive to the crucible used for melting, potassium oxide (K2O) was gradually used to replace part of the lead oxide to make potassium-lead silicate glass (K2O-PbO-SiO2). This kind of glass was more popular from the middle and late Tang Dynasty to the Song Dynasty.

Due to the highly developed culture and art in the Song Dynasty, the shapes of domestic glassware became more colorful. Not only did glass geese, glass grape bunches and other glass imitating the shapes of animals and plants appear, but there were also tripod-shaped objects, egg-shaped objects, glass hairpins and glass hairpins.

Gao Feng: The glass manufacturing industry is developing and production techniques are mature

After the Yuan Dynasty, China's glass manufacturing industry developed. Yanshen Town in Shandong (established as Boshan County in the 12th year of Emperor Yongzheng's reign in the Qing Dynasty) became one of the important glass production areas in the Yuan, Ming and Qing dynasties.

The Qing Dynasty was the peak of ancient Chinese glass manufacturing, which flourished from the Kangxi to Qianlong periods. Glass varieties were diverse and the production process was superb. At that time, there were two centers for glass manufacturing in the south and north of the Qing Dynasty: Guangzhou in the south and Boshan in the north.

In the 35th year of Emperor Kangxi's reign, the Imperial Court set up a "Glass Factory" in the Imperial Household Department, which combined the glass production techniques of the north and south with those of Europe to produce a large number of fine glass products. The glassware shapes were created by combining jade, porcelain and other craft shapes, such as glass water containers, fish tanks, pen holders, etc. The most distinctive of these is the exquisite and artistic glass snuff bottle.

Transparent glass water container from the Kangxi period of the Qing Dynasty

(Photo source: The Palace Museum)

A Qing Dynasty Qianlong Period Glass Body Painted Enamel Dark Eight Immortals Snuff Bottle

(Photo source: The Palace Museum)

In terms of chemical composition, from the 15th to the 19th century, soda-lime silicate glass was the main glass in all parts of the world, while potassium-lime silicate glass and potassium-lead silicate glass were the main glass in the middle and lower reaches of the Yellow River and the Yangtze River in China. This shows the traditional nature of potassium oxide and lead oxide as fluxes in the middle and lower reaches of the Yellow River and the Yangtze River in my country.

While absorbing excellent foreign achievements, ancient Chinese glass manufacturing developed a unique craft path based on its own technological traditions and cultural environment.

Lead-barium silicate glass, potassium silicate glass, and high-lead silicate glass, these ancient glasses with Chinese characteristics have been made into various exquisite objects at different times and have become one of the carriers of ancient Chinese culture, art, and craftsmanship.

These Chinese glass products and manufacturing techniques have also been spread to neighboring countries and regions such as Japan, the Korean Peninsula and Vietnam, and have also become witnesses of cultural exchanges between China and foreign countries. With the development of new archaeological discoveries and various scientific analysis technologies, the history of ancient Chinese glass manufacturing will continue to be written.

References:

Gan Fuxi et al., History of the Development of Ancient Chinese Glass Technology, Shanghai: Shanghai Science and Technology Press, 2016.

Editor: Wang Tingting

Produced by: Science Popularization China

Produced by: Peng Fan (Institute of the History of Natural Sciences, Chinese Academy of Sciences)

Producer: China Science Expo

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