Another important factor affecting cold sintering is how the precipitation process takes place from a supersaturated solution. If the material in solution is chemically bonded to water (e.g. hydroxides, hydrated species…) the precipitation takes place through the formation and de-hydration of a gel. For example, this is the case for silica, which forms silicic acid when it is dissolved in water (SiO2 + 2H2O → Si(OH)4). The precipitation process is strongly analogous to polycondensation, where the loss of water leads to the formation of bridging oxygens.If the material in solution is an electrolyte (chlorides, nitrates and other substances that when dissolved in water or polar solvents form separated anions and cations), the precipitation takes place directly on preexisting crystals or through the formation of new nuclei.