By Stan Aberdeen – Updated March 24, 2022
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Sodium silicate, commonly called “waterglass,” is a versatile material with extensive commercial and industrial uses. It consists of a silicon‑oxygen polymer backbone that can host water molecules within its matrix. Depending on the intended application, it is produced as a solid or a thick liquid.
Unlike simple ionic salts, sodium silicate is a silicon‑oxygen polymer containing ionic sodium (Na⁺) sites. The silicon‑oxygen‑silicon bonds are covalent, giving the material a plastic‑like character. The polar nature of the oxygen and sodium atoms allows the polymer to incorporate water molecules, producing hydrous allotropes (Wells, "Structural Inorganic Chemistry").
The commercial production of sodium silicate typically involves reacting sodium carbonate (Na₂CO₃) with silicon dioxide (SiO₂) at high temperatures that melt both reactants. This process yields a product that is both efficient and scalable for industrial use (Greenwood, "Chemistry of the Elements").
Products from PQ Corporation exhibit densities ranging from 1.6 g cm⁻³ to about 1.4 g cm⁻³. Sodium silicate can appear as a white solid or as liquids with varying clarity—from clear to opaque or even syrupy—depending on manufacturing conditions (PQ, "Sodium Silicates. Products and Specifications").
The uses of sodium silicate vary with grade and formulation. For instance, the Schundler Company highlights its role as a heat‑activated sealant in metal components. When poured into a crack, the liquid “waterglass” infiltrates all crevices; heating to approximately 200 °F drives off water, leaving a hard, brittle seal (Schundler, "Silicate Composites for High‑Temperature Insulation"). Other common uses include fire‑resistant coatings, water‑purification agents, and as a binding material in construction.
Research is underway to leverage sodium silicate’s thermal conductivity for heat dissipation in electronic devices. As electronic circuits become denser, heat management becomes critical. Studies at SUNY explore thermal interface materials, optimal thickness, and pressure conditions to enhance heat transfer and support further miniaturization (SUNY, "Sodium Silicate Thermal Interface").
