The proper diffecation of "Sodium Hydroxide" per The Columbia Encyclopedia, Sixth Edition. 2001.
Sodium Hydroxide
Chemical compound, NaOH, a white crystalline substance that readily absorbs carbon dioxide and moisture from the air. It is very soluble in water, alcohol, and glycerin. It is a caustic and a strong base. Commonly known as caustic soda, LYE, or sodium hydrate, it is available commercially in various solid forms, e.g., pellets, sticks, or chips, and in water solutions of various concentrations; both solid and liquid forms vary in purity. The major use of sodium hydroxide is as a chemical and in the manufacture of other chemicals; because it is inexpensive, it is widely used wherever a strong base is needed. It is also used in producing rayon and other textiles, in making paper, in etching aluminum, in making soaps and detergents, and in a wide variety of other uses. The principal method for its manufacture is electrolytic dissociation of sodium chloride; chlorine gas is a coproduct. Small amounts of sodium hydroxide are produced by the soda-lime process in which a concentrated solution of sodium carbonate (soda) is reacted with calcium hydroxide (slaked lime); calcium carbonate precipitates, leaving a sodium hydroxide solution.
What is metasilicate?
Definition: \Met`a*sil"i*cate\, n. (Chem.)
A salt of metasilicic acid.
Sodium Metasilicate
Sodium metasilicate is not a cleaning agent by itself. It's a strong base (reacts violently with acids). The pH of a 1% aqueous solution is about 13. A major use is as a builder (a material that enhances or maintains the cleaning efficiency of a surfactant, principally by inactivating water hardness) in soaps and detergents.
It may be used as part of a component in a chemical degreaser, where it would react with fatty acids(animal grease) to form a soap, which is then rinsed away.
Sodium silicate, on the other hand, is an abrasive white powder frequently used in things like toothpaste.
Lithium Metasilicate...