We use ethanol extraction. Alcohol extraction of cannabis has been done for centuries. Cannabinoids have excellent solubility in lower alcohols such as ethanol and isopropanol, provided that the water content of the alcohol is low. Ethanol tinctures of cannabis are a part of the US Pharmacopeia, and before prohibition, were readily available for various ailments. While many lower alcohols can be used for efficient extraction of cannabinoids from cannabis, ethanol is the preferred solvent, since it is non-toxic and used in food. Typically, the cannabis is put into a filtration device, and room temperature or slightly colder ethanol is passed through. The ethanol must dehydrated to dissolve the cannabinoids effectively: higher amounts of water reduce the solubility of the cannabinoids and lower the amount extracted. At 80 proof (40% alcohol), very little oil is extracted, due to the much lower solubility of cannabinoids in this water-heavy solvent system.
After extraction, the ethanol is evaporated leaving the cannabis oil as a residue. Heat and vacuum are then applied to remove residual ethanol. This is a highly effective, albeit inefficient process. The end result is a concentrated Botanical extract oil containing most of the phytocompounds with therapeutic value including cannabinoids, terpenes, flavonoids (cannaflavins), aldehydes and more. This extract is usually ~50-80% phytocannabinoids by weight.
Additional refinement can be done via distillation to remove non-cannabinoid components resulting in an extract that is ~80-99% phytocannabinoids. Finally, the distillate can be further processed to remove specific components like THC to create a broad spectrum distillate or non-Botanical components to produce Botanical isolate.