In general, silica sol is a dispersion of nano-silica in water. Its composition is relatively simple, mainly including nano-silica, water and a small amount of stabilizers (Na+, K+, NH4+, etc.), but there are also metal impurities ( Fe2+, Ca2+, AI3+ , etc.) and acid radical impurities (SO42-, CI-, NO3-, etc.) in silica sol.

Silica sol is nano-silica particles with a diameter between 5nm and 150nm, so it has a relatively large specific surface area and adsorption capacity. The viscosity of silica sol is low and the particles are small, so its permeability is very good. When the substance is mixed, the dispersibility and permeability are very good. It is evaporated and concentrated under high temperature conditions, and the colloidal particles are firmly adsorbed on the surface of the object after gelation.