Essential oils have been used across the globe and in every culture on earth for thousands of years. Equipment for the production of aromatic oils by means of steam distillation has been discovered in tombs and ruins over 5,000 years old.
Essential oils are extracted from aromatic plants’ glands, ducts or cells, woody tissue and sap. Generally speaking the most commonly used method is extraction via steam distillation.
However, even for the same plant, the extraction of the oil from different parts of the plant can be different. The therapeutic effects and the risks involved are also different. The various extraction methods are:
Excellent short video from the Discovery Channel on distilling essential oils
Essentially, steam distillation occurs in a big still, not unlike those used for fermenting alcohol. The plant material is loaded into the vessel until it is compacted tightly. Then the container is closed and a boiler is started to inject steam at varying pressures into the bottom. The steam rises, heats and bursts the glands and cells of the plant material releasing the essential oil. To collect that oil a cold pipe is fed through the container causing the steam to condense. Once it is cooled, the water settles, and because oil and water do not easily mix, the essential oil naturally separates and rises to the surface. It is then filtered for greater purity. This is pure essential oil. The leftover mixture of water can also be sold and used as “floral water”.