What is the relationship between sodium metasilicate anhydrous and the common "water glass"?

Sodium metasilicate anhydrous is closely related to the commonly known "water glass" in chemical nature. Water glass, usually referring to the aqueous solution of sodium silicate, is a viscous alkaline liquid widely used in construction, casting, washing and other industries as an adhesive, fire retardant or builder. Its solid form, that is, sodium silicate crystals, can be treated by high-temperature dehydration and other processes to obtain anhydrous sodium metasilicate in powder or granular form. Therefore, water glass can be regarded as an important raw material or intermediate state for the preparation of anhydrous sodium metasilicate.

The two have the same core composition, but their physical forms and usage characteristics are significantly different. Water glass is a liquid mixture containing a large amount of bound water and free water, and its modulus is variable in a wide range. The latter is a strictly anhydrous crystalline compound with a fixed chemical formula of Na₂SiO₃, almost no free water or crystal water, with a definite crystal structure and higher chemical purity. When solid, high-purity, and easy-to-measure sodium silicate products are needed, water glass is not as suitable as sodium metasilicate anhydrous.

At the application level, sodium metasilicate anhydrous and water glass also have their own focuses. Although water glass solution is easy to use, solid anhydrous sodium metasilicate has more prominent advantages in certain specific industrial fields. It can also provide silicate ions and alkalinity after dissolution, and because of its high purity, single component, and good fluidity, it is particularly suitable for use as a high-efficiency detergent aid, ceramic binder, metal cleaning agent, and bleaching stabilizer. These advantages of anhydrous sodium metasilicate make it a high-value-added silicate product formed after deep processing of water glass. In short, anhydrous sodium metasilicate is a refined solid form obtained by dehydration and crystallization of water glass, which is convenient for specific application scenarios.