Aromatherapy is a practice that has been used since ancient times. Many people use aromatherapy to provide a relaxing scent in a room or on the body. Certain essential oils are also used for medicinal purposes in incense and ointments. Essential oils derived from wood such as cedarwood and cypress are used in massage oils, skin lotions and vapor rubs. Essential oils can be extracted from wood using cold press, dry distillation or hydrodistillation.
Dry distillation is a process that uses a high amount of heat to extract oils from harder woods. The process starts with a direct flame applied to a pot or vat of the wood material. When the oils in the wood begin to evaporate, they are collected in a vapor pipe and condensed to turn the vapor back into liquid form. Essential oils derived in this way will also contain hints of a smoky odor since the high temperatures have a tendency to burn some of the wood during the process.
The most common essential oils produced with this method are birch tar oil and cade oil.
Another method of extracting oils from woods is hydrodistillation. It is similar to the dry distillation process except large amounts of water are added at the beginning of the process. Hydrodistillation starts with the wood or plant material being submerged into water. The material will soak for a few hours--up to a day--before heat is applied to the mixture.
The second part of hydrodistillation is the same as the dry distillation method. The mixture is heated in a large vat until the water and essential oils together begin to evaporate. The vapor is collected and condensed. Hydrodistillation is used for nuts, roots and wood materials, but can also have a stronger smoky smell than a dry distillation method.
A third method for extracting essential oils from wood materials is the cold-pressed method. This method works well for woods, nuts and citrus rinds. It works by using a mechanism to press the oils out of the material. The first stages of the pressed oil will contain an extra amount of water, but this water generally evaporates after a few hours.
The cold-pressed method works well for those who need to use the essential oils quickly. Cold-pressed essential oils have a short shelf life and can spoil more quickly than those from other methods of extraction.