Commonly known as "water-glass", soluble sodium silicates are colorless low cost inorganic materials. When used as adhesives, liquid silicates offer significantly low cost, versatility, and ease of handling. Their main use is to bond porous substrates such as paper and cardboard where an inexpensive, fast processing adhesive is required. Other adhesive applications for sodium silicates include bonding of wood, metal foils or glass to porous substrates, glass fiber insulation bonding, as well as the fabrication of foundry molds and abrasive wheels. Because of its inorganic nature sodium silicates can be formulated into industrial cements with exceptionally high resistance to temperatures and chemicals.
Sodium silicate adhesives are usually supplied as a viscous water solution. The adhesive bond forms by (1) the evaporation of water and / or (2) chemical reaction. Sodium silicate water solutions are often used directly as an unmodified adhesive, but they can also be blended with polymeric additives to improve specific properties such as toughness.
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