Essential oils are extracted from plants. Plants, woods, spices and herbs are main sources of natural essential oils. Distillation is the main source of getting the oil from the plant.
Distillation works well with roots, berries, and leaves. Sometimes, in the cases with wood, oil can be released when it is burnt. This was a popular technique with Indians, who used this aromatherapy method often.
Steam distillation is the most common method used to extract natural essential oil.
A flow of steam is put in to a chamber that is holding the raw plant
material. That steam causes small sacs in the plant to burst, releasing
essential oil.
The steam carries the oil out of the chamber and in to a condenser that
is chilled. The steam becomes water once it hits the cooled condenser.
At this point the water and oil are separated.
The water portion of the plants, or the cooled down steam, is known as hydrosol. Hydrosol is not wasted, or thrown away, since it still contains a small portion of the plant essence. Hydrosol can be used for different reasons, such as being used for their soothing properties or aroma.
There are a few different important factors in regards to how good the quality of distilled essential oil is. First, the temperature and pressure is important to how successful the distillation process is. The temperature of the extraction chamber needs to be monitored on a constant basis.
The reason is because the extraction chamber cannot have too high a temperature. Otherwise, the components of the oil might be ruined or altered. The pressure of the chamber also needs to be the correct pressure so it is not too harsh or lesson the oil's effects.
When extracting natural essential oil it is important to take the time to make sure that all the oil components are flushed out of the plant. Some plants will release their oil more quickly than others. You can notice the difference between essential oils that are compared side-by-side with aggressive processing and slow processing.