What is Sodium Metasilicate Pentahydrate and what is it used for


Sodium Metasilicate commonly shortened to Metso, is formed by the high temperature fusion of sodium carbonate and silicon dioxide. Sodium Metasilicate forms highly alkaline solutions when dissolved in water. It is commonly used as a component of cleaners such as dishwasher detergent and laundry detergent.


  • Other Names: Silicic acid disodium salt pentahydrate, Disodium silicate pentahydrate, Sodium silicate hydrate, Disodium trioxosilicate
  • Appearance: Colorless or white crystal
  • Odour: Odourless
  • Melting Point: 72.2  ° C
  • Specific Gravity: 0.7 ~ 1.0 g/ cm3
  • PH: Basic
  • Solubility: 610g / l in water (@ 30 o C)
  • CAS NO: 10213-79-3
  • Molecular formula: Na2SiO3 · 5H2O
  • Molecular weight: 212.13
  • Alkali Content (as Na 2 O): 28.0% ~ 30.0%
  • Content as (SiO 2 ): 27% ~ 29%
  • Degree of Whiteness: 75.0 % Min
  • PH Value(1 % at 20): 12.4–12.6
  • Fe: 200 ppm max
  • Water insolubles: 0.2% max

It is considered to be safer to use than sodium hydroxide (caustic soda) and does not attack metals including aluminium as aggressively as caustic. It moderates the tendency of the alkali to corrode and dissolve metals. Sodium silicate reacts with metal oxides to form a protective film on metal surfaces. This film is maintained as long as small amounts of soluble silica remain in the presence of water.

When used in conjunction with surfactants / detergents sodium metasilicate aids 1. The neutralization of acidic soil 2. The emulsification of oily and greasy soil 3. The deflocculation of particulate soil 4. The suspension of removed soil and prevention of it’s redeposition.

Sodium metasilicate disperses grease and dirt deposits into small suspended particles that rinse away without redepositing on freshly washed surfaces


A major use is as a builder (a material that enhances or maintains the cleaning efficiency of the surfactant, principally by inactivating water hardness) in soaps and detergents. Mainly used in making high efficiency detergents and metal cleaners. As a substitute for STPP, it can increase cleaning efficiency and reduce environment pollution, it provides excellent alkaline buffering, corrosion prevention for metal (i.e. Zinc, Aluminum), and aids in the of softening water. Used to improve washing detergents and metal cleaners.

It is also used extensively as an anti-corrosion agent in boiler-water feed.

Sodium metasilicate is used in fireproofing mixtures; in laundry, dairy, metal, and floor cleaning; in deinking paper; in washing carbonated drink bottles; in insecticides, fungicides, and antimicrobial compounds; as a chemical intermediate for silica gel catalysts; as an ingredient in adhesives; as a bleaching aid; and as a boiler compound. Combined with other salts such as sodium bicarbonate, it can be applied to aluminum as a paint stripper.

The pentahydrate form is considered as safe by the Food and Drug Administration (FDA) for use in washing mixtures for fruits and vegetables, in sanitizing solutions for food-contact surfaces, in boiler water, as a denuding agent for tripe, as a hog scald agent for the removal of hair, and as a cooling and retort water agent for the prevention of staining of the outside surfaces of canned goods.

Health & Safety

R38– Irritating to skin. R41– Risk of serious damage to eyes.

See MSDS for sodium metasilicate pentahydrate for full details

Where to Buy Sodium metasilicate / Metso online



About mistralhowto

formulation chemist

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