Solvent extraction is often used for gums
and resins, but also for other plant
materials. It involves covering the
plant material in a solvent, which may be
a petrochemical, and then extracting the
essential oil by filtering the plant
material and evaporating the solvent.
While this method may be perfectly
acceptable to the perfume trade, good
aromatherapy companies try to avoid buying
essential oils and absolutes produced
using petrochemical solvents.
