The Art and Science of Essential Oil Distillation and Herbal Preparations
Essential oils are the distilled aromatic molecules of plants. There are several different methods of distillation used to draw these aromatic essences out of plant material.
Technically, only steam distilled essences are “essential oils,” yet it is common parlance in aromatherapy to refer to all distilled plant oils as “essential oils.” We follow this standard, too, and refer to all aromatic plant oils as essential oils except for absolutes as these oils are used only in perfumery and not in culinary creations or in skin care. All essential oils are the lipophilic liquids of the parent plant material.
For clarity and key information sharing, in the “Details” section of every essential oil description on the Living Libations website we list the extraction method used in the creation of the oil.
Most essential oils are made through steam distillation. This distillation process turns these pure molecules into a vapor that is then condensed back into liquid form.
This is how that process works: the appropriate plant matter (herbs, roots, berries, or flowers) is put in a large stainless steel or glass container that has holes in the bottom. Steam from boiling water in a furnace below the alembic rises up through the holes, moves through the herbs, and collects the aromatic plant molecules. Then the steam moves up through tubes at the top of the pot into a condenser. The steam is cooled and condensed into a liquid called a hydrosol (in the distillation of rose essential oil for example, the remaining hydrosol is more familiarly known as rosewater). The essential oils are collected off the top of the hydrosol.
Attar is a beautiful ancient method of steam distilling. The attar method was invented in the 12th century by Farid od Din Attar of Persia who was a perfumist, a physician, and a poet as well. Attar distillation pairs plant matter (usually a delicate flower), with sandalwood during the steaming process. This distillation process usually takes about 25 days. The most well-known attar is Rose Attar.
Some distilleries use hydro-distillation to process woody plant materials such as tough roots, twigs, and hard spices. Hydro-distillation is slower and uses lower temperatures to keep the chemical compounds in the oils from denaturing. The plant material is first soaked in water and then the temperature is slowly increased until steam is produced. The aromatic molecules are released in the steam, cooled, condensed, and collected.
This is the simplest and purest method for creating oils from the peel of a fruit, especially citrus oils. The whole fruit is put in a mechanism that makes thousands of micro-pierces in the peel to rupture the cells that contain the aromatic oils. Then the whole fruit is pressed to release the juice and the oils. This lovely liquid is centrifuged to separate the fruit solids, juices, and oil. The oil is siphoned off the top into another container.
Extraction style distillation uses a solvent to help release the aromatic molecules from the plant material. An extraction method is generally reserved for aromatic essences that cannot successfully release their essence through steam distillation, such as vanilla, myrrh, carnation, tuberose, tonka bean, and lilac. There are a few types of extraction, and the most common are CO2 and absolute.
Some delicate plants produce a very low yield with steam distillations yet the process of absolute extraction with hexane as the solvent can pull more of the essences out of the plant. In this process, delicate flowers are arranged on a wire mesh or a perforated tray and then washed with the solvent. The solvent dissolves part of the plant material leaving behind a waxy substance. This waxy stuff is mixed with alcohol and then strained. The essential oils stay in the alcohol. All of the hexane is removed after the distillation process, and it is even recycled and used again and again.
Although absolute oils used food grade hexane and are available to the food and flavor industries, we like to use absolutes solely for their exquisite use in perfumery and diffusion.
Supercritical Extraction: CO2
There is a more modern and exciting extraction technique that uses pure liquid carbon dioxide to extract plant oils called supercritical extraction, which pulls out larger molecules from the plant resin than the steam distillation process and it does not expose the plant oils to heat nor hexane – just pressure.
When put under pressure, carbon dioxide turns from gas to liquid. Plant material is then immersed in this liquid CO2 and most of the plant material dissolves and the oils mix with the liquid CO2. Then the pressure is released and the CO2 returns to a gas and leaves the beautiful and potent extract of essential oils behind.
Hydrosols or Waters
A hydrosol is the watery and wonderful byproduct of steam distillation. When steam moves up through the plant material and into tubes at the top of the distilling pot, it goes into a condenser where it is cooled and condensed into liquid. The essential oil separates to the top of the watery liquid, which is the hydrosol.
Hydrosols contain traces of the aromatic essences as well as the water-soluble properties of the distilled plant. Frankincense and Rosewater are the best hydrosols for skincare.
Tinctures, Infusions, and Decoctions,
Another way to extract a plant’s chemical compounds, is to soak the plant matter to make tinctures, infusions, and decoctions. For these methods, plant matter is bathed in oil or alcohol as the carrier liquid is saturated with botanical compounds and is then strained.
Flower essences are energetic extracts created by soaking pristine flowers in jars of water that are sensitively placed in the sun to allow the flowers to leave their botanical imprint on the water. The flower-water is then diluted with organic grape alcohol. Flower essences are gentle, energetic means of supporting mind-body issues, wellbeing, and spiritual growth. Each flower species imbues a distinct imprint on the water, and these imprints correspond with particular vibrations.
Tinctures are extracts of plants made with soft plant material steeped in alcohol.
An infusion is like a tea, where soft volatile herbs are macerated and steeped for long periods of time in a hot liquid like water or oils.
A decoction differs from an infusion only in that the liquid and herbs are boiled together, similar to making vegetable stock. This method is frequently used with hard plant material like bark and roots that need some coaxing to release their volatile substances.
Silky smooth carrier oils are the oily-oils squeezed from the seeds and kernels that plants form after flowering. They are rich in lipids and essential fatty acids and absorb quickly into the skin for deep moisture and nourishment. Therapeutic on their own, these emollient oils are also the perfect vessels to "carry" essential oils to the body. Carrier oils are used to dilute, lubricate application, and slow the evaporation rate of essential oils.
Nadine Artemis, the founder of Living Libations, is the author of Holistic Dental Care: The Complete Guide to Healthy Teeth and Gums, and Renegade Beauty: Reveal and Revive Your Natural Radiance, which was named one of “The Top 10 Books on Skin Care” by The Strategist of New York Magazine. She is a respected media guest and contributor, and her products have received rave reviews in the New York Times, LA Times, Elle, People, Vogue, and Hollywood Reporter. Described by Alanis Morissette as “a true-sense visionary,” Nadine crafts elegant formulations and healing creations from rare botanicals that have skin glowing around the world. Her concept of Renegade Beauty encourages effortlessness and inspires people to rethink conventional notions of beauty and wellness.