There are several different types of extraction methods for CBD, including manual separation, solvent extraction, ethanol extraction, vegetable oil extraction, and CO2 extraction. The safest method of extraction is the CO2 method, because CO2 is non-volatile. Plant material (in this instance, hemp) is ground and placed in an extraction vessel. CO2 gas then undergoes high temperature and pressure, which forces it into the extraction vessel through a pump. When it moves into the vessel, it starts to dissolve the plant material. After that, a pressure relase valve allows the broken down material to move into a separate vessel with an internal compressor and heater to adjust the pressure and temperature. This allows certain molecules to bond with the CO2, allowing them to be separated from the plant material.