Solvent Extraction involves using ethanol, butane, or CO2 to extract the cannabinoids from the plant. The cannabis is placed in the solvent until the cannabinoids dissolve, creating a solution that is then filtered to strain out any remaining plant material. The strained solvent is then evaporated, which leaves behind the extract that contains the cannabinoids.
Supercritical CO2 Extraction uses carbon dioxide to extract the cannabinoids, like that of the Solvent Extraction process. However, in Supercritical CO2, the CO2 is pressured and heated until it becomes a liquid and gas combination. The cannabis is then soaked in this supercritical CO2, dissolving the cannabinoids. After the resulting solution is collected, the CO2 evaporates, leaving behind the extract containing the cannabinoids.
Steam Distillation uses steam to extract the cannabinoids from the plant, passing through the plant material, which causes the oils and cannabinoids to evaporate. The water vapor that is then left behind is collected and condensed, which separates the cannabinoids from the water for collection.
Rosin Press involves using heat and pressure to extract the cannabinoids from the plant, by placing the plant material between two heated plates, which are then pressurized. This process causes the cannabinoids to liquify and seep out of the plant, as an extract which is then collected.
While all these differing methods are highly effective ways of extracting cannabinoids, results can vary. The experience of the extractor, the equipment, and the plant can all affect the quality, purity, and the yield of the cannabinoids extracted.
Sources: Science Direct, Nature, Bloom Medicinals, Weedmaps