Essential oils are made using a variety of extraction methods. The two main methods for actually making essential oils are through a cold pressed extraction as well as steam distilled extraction. Learning the difference between these two could help you get access to some better essential oils for your health and aromatherapy needs. Here are some details on each one of these processes:
Cold pressing is used primarily in citrus essential oils and it's otherwise known as expression. The process of extracting oil from citrus fruits involves a machine today. In the past this would've been done by hand. The rind of the citrus fruit will be placed in a container with spikes and prods. As the spikes continue to puncture the rind the entire device is rotated so that the essential oil can collect into a small container below the container that houses the rinds. The spinning process works similarly to a centrifuge and it will separate the most usable sources of oil from the citrus fruit.
Another common method involves steam distillation. This method is more commonly used with plant life like herbs and flowers. The idea of this process involves placing the rind of a citrus fruit or the leaves of herbs or a plant on a grate. Steam is then introduced inside of a chamber and as it is injected under a high-pressure the essential oils are then collected as a byproduct of the steam.