Architectural glass light in industrial factories. Annealed glass is glass without internal stresses caused by heat treatment, i.e., rapid cooling, or by toughening or heat strengthening. Glass becomes annealed if it is heated above a transition point then allowed to cool slowly, without being quenched. Float glass is annealed during the process of manufacture. However, most toughened glass is made from float glass that has been specially heat-treated. Annealed glass breaks into large, jagged shards that can cause serious injury and is considered a hazard in architectural applications. Building codes in many parts of the world restrict the use of annealed glass
Ancient Chinese glass these forms were normally made out of lacquer or ceramic, although some jade vessels in those shapes are also known. All vessels were produced by mould casting. Ancient Chinese glass Ancient Chinese glass refers to all types of glass manufactured in China prior to the Qing Dynasty (1644–1911). In Chinese history, glass played a peripheral role in the arts and crafts, when compared to ceramics and metal work. The limited archaeological distribution and use of glass objects are evidence of the rarity of the material. Literary sources date the first manufacture of glass to the 5th century AD. However, the