The use of sodium silicates as gluing binders is limited by the fact that the tensile strength of these bindings
is below 50 kg/cm2, and the fact that the bindings remain water-soluble till the annealing temperature of +250°C. Besides, when heated to +160°C , these gluing binders distend. Gluing binders based on SiO2 sold or gels exhibit tensile strength above 500 kg/cm2, are insoluble in water at the annealing temperature of +150°C and do not distend during heating