CO2 extracts display some of the characteristics of both essential oils and absolutes. Like essential oils, they contain many beneficial therapeutic properties. But unlike absolutes, they are not solvent extracted. Instead of hexane, they are extracted using CO2 (carbon dioxide) gas under pressure at ambient temperatures. Under normal atmospheric conditions CO2 is a gas, but in the presence of high pressure it is compressed until it has the density of a liquid and becomes supercritical carbon dioxide – neither a gas nor a liquid. It is while in this supercritical phase that CO2 acts as a “solvent” to extract aromatic oil from plants. The beauty of CO2 extraction is that once the oil is extracted from the plant material, the CO2 is simply returned to its gaseous state by lowering its pressure, allowing the gas to quickly and completely dissipate.
*taken from Eden Botanicals