Of various methods wet chemical processes are the laboratary methods of manufacturing nanomaterials. These include colloidal chemistry, hydrothermal methods, sol-gels, and other precipitation processes. Solutions of different ions are mixed in well-defined quantities and under controlled conditions of heat, temperature, and pressure to promote the formation of insoluble compounds, which precipitate out of solution. These precipitates are then collected through filtering and/or spray drying to produce a dry powder.The advantages of these wet chemical processes are that a large variety of compounds can be manufactured, including inorganic, organics, and also some metals, using cheap equipments and in significant quantities. Another important factor is the ability to control particle size closely and to produce highly monodisperse materials. However, there are limitations with the range of compounds possible; bound water molecules can be a problem, and, especially for sol-gel processing, the yields can be quite low.