Sodium Silicate is the common name for a compound sodium metasilicate, Na2SiO3, also known as water glass or liquid glass. It is available in aqueous solution and in solid form and is used in cements, passive fire protection, refractories, textile and lumber processing, and automobiles. Sodium carbonate and silicon dioxide react when molten to form Sodium Silicate and carbon dioxide.

For metal repair, Sodium Silicate is used, along with magnesium silicate, in muffler repair and fitting paste. When dissolved in water, both Sodium Silicate, and magnesium silicate form a thick paste that is easy to apply. When the exhaust system of an internal combustion engine heats up to its operating temperature, the heat drives out all of the excess water from the paste. The silicate compounds that are left over have glass-like properties, making a temporary, brittle repair.

For automotive repair, Sodium Silicate can be used to seal leaks at the head gasket. A common use is when an alloy cylinder head engine is left sitting for extended periods or the coolant is not changed at proper intervals, electrolysis can "eat out" sections of the head causing the gasket to fail.

For car engine disablement, Sodium Silicate solution is used to inexpensively, quickly, and permanently disable automobile engines. Running an engine with two quarts of a sodium silicate solution instead of motor oil causes the solution to precipitate, catastrophically damaging the engine's bearings and pistons within a few minutes.

For adhesive uses, Sodium Silicate was used to seal combustible nitrated paper together to form a conical paper cartridge to hold the black powder, as well as to cement the lead ball or conical bullet into the open end of the paper cartridge. Such Sodium silicate cemented paper cartridges were inserted into the cylinders of revolvers, thereby speeding the reloading of cap and ball black powder revolvers.

For aquaculture uses, Sodium Silicate gel is also used as a substrate algal growth in aquaculture hatcheries.

For food preservation, Sodium Silicate is used as an egg preservation agent. When fresh eggs are immersed in it, bacteria which cause the eggs to spoil are kept out and water is kept in. Eggs can be kept fresh using this method for up to nine months. When boiling eggs preserved this way, it is well advised to pin-prick the egg to allow steam to escape because the shell is no longer porous.

For drilling fluid uses, Sodium Silicate, also known as waterglass, is frequently used in drilling fluids to stabilize borehole wells and to avoid the collapse of bore walls. It is particularly useful when drill holes pass through argillaceous formations containing swelling clay minerals such as smectite or montmorillonite.

For Passive Fire Protection (PFP) uses, Sodium Silicates are inherently intumescent. They come in prill (solid beads) form, as well as the liquid, water glass. The solid sheet form (Palusol) must be waterproofed to ensure longterm passive fire protection.