Distillation: Converts the volatile liquid (the essential oil) into a vapor and then condenses the vapor back into a liquid. It is the most popular, and cost effective method in use today in producing essential oils.
Water Distillation: The botanic material is brought to the boil. The surrounding water acts as a barrier to prevent it from overheating. When the condensed material cools down, the water is separated and the oil decanted to be used as essential oil.
Steam Distillation: The botanic material is placed in a still and steam is forced over the material. The hot steam helps to release the aromatic molecules from the plant material since the steam forces open the pockets in which the oils are kept in the plant material. The molecules of these volatile oils then escape from the plant material and evaporate into the steam. The steam passes through a cooling system where the essential oil and water is then separated.
Hydrolats: These are the by product of the distillation process, often made with spring water. They contain a small amount of essential oil. They have similar properties to the corresponding essential oil and can be used neat on the skin. They are ideal to use as skin toners.
Expression: Traditionally this method was used to obtain oils from citrus fruits. The peel was squeezed by hand, which released the oil and was then collected in sponges. Nowadays, this method may be carried out by machinery.
Enfleurage: This method is time consuming and expensive. It is only usef for more expensive oils from delicate blooms, such as rose and jasmine. Fat is spread in a thick layer over sheets of glass. The fat is covered with the petals and the stacked. The process continues for several days until the fat is throughly saturated with the essence of the petals. The term pomade is used to describe the mixture. This pomade is washed in alcohol which is then evaporated or separated. What remains is know as an enfleurage. Oils produced by this method are know as 'absolutes' and are highly concentrated essential oils.
Solvent Extraction: It is a gentle extraction method and is used mainly where steam distillation would spoil the delicate fragrance. Liquid butane or liquid carbon dioxide, is used to dissolve the essential oils. When the solvent is removed what remains is called a concrete. This is washed with pure alcohol and then evaporated to remove the plant waxes and a high quality absolute is left behind.
Hydrodiffusion/ Percolation: This is a relatively new way of extracting essential oils from plants. Steam passes down through the plant rather than up. This method is useful for extracting oils from woody and tough plants parts, such as seeds. It produces better quality oil than steam distillation.
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