Silicates are water-based solutions of polymeric silica. When properly applied, sodium silicates penetrate the surfaces to be joined. Liquid silicates begin to dry by losing moisture to the air and to the substrate itself. As this occurs, the viscosity increases becoming tacky and sticky. Eventually the silicate dries to form a hard, glasslike bond. In addition to bonding, the silicates harden and strengthen the substrates.
Silicates usually work well with porous or semi-porous surfaces, where the silicate can partially penetrate the surface. Silicates can also bond metal and glass, but surfaces must be roughened or attacked chemically to make sure that a good physical bond can be formed. Typical applications include: adhesive for corrugated board, tubewinding and foil-to-paper lamination adhesive.