The Silk Road was a channel for cultural exchanges between China and the West in ancient times, in which glass was a valuable material evidence of early trade. Early glass was often made into beaded ornaments in West Asia and Egypt, and was introduced to China. After absorbing its technology, China ancient glass used local materials, so it was similar to foreign glass products in appearance, but its chemical composition was different.
The main raw material of glass is quartz sand, and the main chemical component is silicon dioxide (SiO2). Due to the high melting point of pure quartz sand, in order to reduce the melting temperature, flux should be added during refining. In ancient times, plant ash, trona, saltpeter and lead ore were commonly used as flux, and limestone was added as stabilizer, which was converted into calcium oxide (CaO) after calcination.
The main chemical composition of the added flux is different. For example, lead-barium glass is added with lead ore as a flux in the firing process, and its content of lead oxide (PbO) and barium oxide (BaO) is high, which is usually considered as a glass variety invented by China himself. Lead-barium glass is the main glass in Chu culture. Potassium glass is mainly popular in Lingnan, Southeast Asia and Indian regions, with plant ash and other high-potassium substances as flux.
What are the ancient glass products?
1, glazed sand beads
After the Warring States Period, real glass products began to appear in China, and glazed sand products gradually disappeared. In the tombs in the late Spring and Autumn Period and the early Warring States Period, people not only found the typical western soda-lime silicate glass (Na2O-Cao-SiO _ 2)- dragonfly eye glass beads, but also found the unique potassium-lime silicate glass (K2O-Cao-SiO _ 2) in ancient China. The glass inlaid by the famous Yue King Gou Jian's sword lattice belongs to potassium calcium silicate glass.
2, lead barium silicate glass
During the Warring States Period, lead-barium silicate glass (PBO-Bao-SiO _ 2) and potassium silicate glass (K2O-SiO _ 2) developed in the Yangtze River valley.
Lead-barium silicate glass is internationally recognized as the most unique glass system in ancient China. They are silicate glasses with lead oxide (PbO) and barium oxide (BaO) as main fluxes, and their main raw materials are quartz sand (mainly composed of SiO2 _ 2), galena (mainly composed of PbS), barite (mainly composed of BaSO4 _ 4 _ 4) and saltpeter (mainly composed of KNO3 _ 3).
3. Glass
During the Sui and Tang Dynasties, glass-making technology was further spread and developed, and daily utensils such as glass bottles, glasses and glass plates increased. At the same time, influenced by Buddhism, a large number of glass relic bottles also appeared.
The main raw material of glass is quartz sand.