Sodium silicate is the common name for a compound sodium metasilicate, Na2SiO3, also known as water glass or liquid glass. 37.5% solution in water. It is available in pint or gallon size as a semi-viscous alkaline solution. It is used in ceramic casting slip as a deflocculant, as a hardener in fireclay cements & refractories, for stiffening or repairing fiber blankets, and for cash for clunker automobile disablement.