Also known as window glass. Flat glass with light transmission, heat insulation, sound insulation, wear-resistant, weather-resistant function, some also have insulation, endothermic, radiation and other characteristics, and thus widely used in mosaic buildings doors and windows, walls, interior decoration. The specifications of the flat glass are usually divided into 2mm, 3mm, 4mm, 5mm, and 6mm, as well as the production of 8mm and 10mm. General 2mm, 3mm thick for civil buildings, 4mm-6mm for industrial and high-rise buildings. The main defects affecting the quality of flat glass are bubble, stone and wave rib. Bubble is the latent floated in the vitreous, which is produced during the cooling stage of the manufacturing process. Stone commonly known as lump, also known as sand, is in the glass of solid inclusions, which is the most dangerous in the vitreous defects, it not only destroys the appearance of glass and optical uniformity, and will greatly reduce the mechanical strength and heat of glass products, and even make the product itself fragmentation.