Glass yarn is made by eight types of stones including pyrophyllite (or kaolinite), calcite, colemanite and quartz sand etc. The mixture of the stones is heat in furnace at 1600℃ and become liquid glass. The liquid glass will turn to glass filament with diameter around 5-9 micron meter through platinum bushing plate. By twisting glass filaments together, glass yarn could be made. Glass yarn is widely used as insulating material due to its mechanical and electrical properties.