Essential oils are primarily obtained by distillation. A distillation unit consists of several pipes and flasks, usually made of glass or copper. With the exception of citrus fruits, all essential oils are obtained by distillation. There are two main types of distillation: steam and hydrodistillation.
Steam distillation is a process in which water is placed in a separate boiling flask or container below the plant material flask. The water is heated to create steam, which travels up and through the plant material. The steam rises up through the piping into the condenser, where it drips down as a liquid. The liquid is collected at the bottom of the pipe, where the oil will remain separated from the water.
Hydrodistillation is a process in which the plant material is placed in a flask of water. The water containing the material will be heated to a specific temperature to boil and create steam. Like steam distillation, the steam travels through the condenser and down to be collected. The separated oil will be collected after the distillation.