Sodium silicate
These compounds are generally colorless transparent solids or white powders, and soluble in water in various amounts.
The commercial product, available in water solution or in solid form, is often greenish or blue owing to the presence of iron-containing impurities.
Soluble silicates of alkali metals (sodium or potassium) were observed by European alchemists in the 16th century.
Giambattista della Porta observed in 1567 that tartari salis (cream of tartar, potassium bitartrate) caused powdered crystallum (quartz) to melt at a lower temperature.
[5] When the powder was exposed to moist air, it gradually formed a viscous liquid, which Glauber called "Oleum oder Liquor Silicum, Arenæ, vel Crystallorum" (i.e., oil or solution of silica, sand or quartz crystal).
[7] That would have been prepared in 1818 by Johann Nepomuk von Fuchs, by treating silicic acid with an alkali; the result being soluble in water, "but not affected by atmospheric changes".
[citation needed] Heated to drive off the water, the result is a hard translucent substance called silica gel, widely used as a desiccant.
[citation needed] Solutions of sodium silicates can be produced by treating a mixture of silica (usually as quartz sand), caustic soda, and water, with hot steam in a reactor.
The main applications of sodium silicates are in detergents, paper industry (as a deinking agent), water treatment, and construction materials.
Sodium silicate binds to colloidal molecules, creating larger aggregates that sink to the bottom of the water column.
When mixed with finely divided mineral powders, such as vermiculite dust (which is common scrap from the exfoliation process), one can produce high temperature adhesives.
The intumescence[clarification needed] disappears in the presence of finely divided mineral dust, whereby the waterglass becomes a mere matrix.
Sodium silicate is used as a deflocculant in casting slips helping reduce viscosity and the need for large amounts of water to liquidize the clay body.
The silicate compounds that are left over have glass-like properties, making a temporary, brittle repair that can be reinforced with glass fibre.
Sodium silicate is frequently used in drilling fluids to stabilize and avoid the collapse of borehole walls.
[29] A chemical reaction occurs with the excess Ca(OH)2 (portlandite) present in the concrete that permanently binds the silicates with the surface, making them far more durable and water repellent.
This treatment generally is applied only after the initial cure has taken place (approximately seven days depending on conditions).
This phenomenon has been used by manufacturers of toys and chemistry sets to provide instructive enjoyment to many generations of children from the early 20th century until the present.
An early mention of crystals of metallic salts forming a "chemical garden" in sodium silicate is found in the 1946 Modern Mechanix magazine.
[31] Metal salts used included the sulfates and/or chlorides of copper, cobalt, iron, nickel, and manganese.
Sodium silicate with additives was injected into the ground to harden it and thereby to prevent further leakage of highly radioactive water from the Fukushima Daiichi nuclear power plant in Japan in April, 2011.
[32] The residual heat carried by the water used for cooling the damaged reactors accelerated the setting of the injected mixture.
[33] A historical use of the adhesive properties of sodium silicates is the production of paper cartridges for black powder revolvers produced by Colt's Manufacturing Company between 1851 and 1873, especially during the American Civil War.
Reloading brass shotgun shells was widely practiced by self-reliant American farmers during the 1870s, using the same waterglass material that was also used to preserve eggs.
It works like water cement, once the muscle starts to move, it cracks and leaves white residues on the skin.
[36] Sodium silicate's flocculant properties are also used to clarify wine and beer by precipitating colloidal particles.
As a clearing agent, though, sodium silicate is sometimes confused with isinglass which is prepared from collagen extracted from the dried swim bladders of sturgeon and other fishes.
