Sodium silicate, also known as sodium metasilicate, is an inorganic substance with the chemical formula Na₂SiO₃. Its aqueous solution is called water glass, and it comes in colorless, greenish, or brown solids or viscous liquids. It is widely used in foundry, papermaking, sand casting, mold making, paper tube and box adhesives, construction, carbon black, subway construction, gold and silver foil lamination, ceramics, and alkali for silicate sol, among others. It can also be customized into various liquid sodium silicate products according to customer requirements.