Essential oils are the concentrated vital essences of aromatic plants used in cosmetics, perfumes, flavourings, and in aromatherapy. Known as volatile oils, the essential oils of a plant are the aromatic oils responsible for flavour and aroma in such herbs as mints, citrus, and spices. Although called “oils”, they are more like water as they are a liquid that readily evaporates or volatilize. The fixed oils in a plant do not evaporate.
Volatile, or essential, oils are found in minute glands in one or more parts of the plants:
- *leaves (e.g. basil)
- *flowers (e.g. rose)
- *fruit (e.g. lemon)
- *seeds (e.g. coriander)
- *wood (e.g. sandalwood)
- *resin (e.g. frankincense)
- *bark (e.g. cinnamon)
- *roots (e.g. Calamus)
Most oils are extracted by distillation (steaming) or enfleurage (in grease). Both methods are time-consuming and labor-intensive and require expert use of complicated equipment and top-quality materials. Huge amounts of plant stock are needed to distill minute quantities of oil. For example, it takes about 250 pounds of rose petals to produce one fluid ounce of essential oil. For these reasons, it is not worth attempting home extractions, and the rationale behind the high cost of these oils. However, for the curious, the methods are described below — which will only serve to confirm what was said previously — it is hardly worth the effort!
For the past few centuries, the world’s essential oil industry has been centered in the town of Grasse, in southern France. A French chemist, Professor Ren -Maurice Gattefosse, is credited with originating the term “aromatherapy” during WWI. Madame Maury, a biochemist and student of Gattefosse, developed the massage techniques and formulas now associated with aromatherapy.
As mentioned earlier, cost of the oils vary exceedingly. For example, jasmine, neroli, and rose oils are about 150 to 175 times the cost of camphor, sweet orange, and eucalyptus. Most oils are two or three times the cost of camphor. If a selection of oils is offered at the same price, be suspicious.
Never buy oils that have been displayed in a hot, sunny window, or in clear glass. They must be stored in airtight, dark glass containers in a cool, dark place, but not in a refrigerator. Most essential oils are sold in ml size bottles. One ml equals about 20 drops of essential oil.
Oils labled “aromatherapy oils” are a mixture of about 2% essential oil in a carrier oil, meant for massage purposes. Once essential oils are added to carrier oils, their shelf life is reduced from years to a few months. To a 2-ounce bottle of carrier oil, add between 15 and 30 drops of essential oil. The usual is about 25 drops. Carrier oils are used to dilute an essential oil, since using essential oil full strength on the skin is a dangerous practice and should never be done. Full strength essential oils are not only irritating to the skin, but, in some cases, can be absorbed to cause damage internally.
- Almond oil is the most popular as it has little odour, is rich in protein, and is emollient, nourishing, and slow to become rancid.
- Apricot or peach kernel oils have the same properties as almond oil but are more expensive.
- Grapeseed oil is fine and clear and gives a satin-smooth finish without a greasy touch.
- Hazelnut oil penetrates the skin easily and deeply.
- Jojoba oil keeps well and is satin smooth on the skin.
- Olive oil is a strong scented oil and can overpower the fragrance of essential oils.
- Sesame oil keeps well but has a strong odour.
- Corn, soy, and sunflower oils are acceptable.
- Soy has a pleasant feel and does not become sticky with pressure.
- Sunflower has the least keeping qualities but contains vitamin F.
The following oils are often added in small quantities to a massage mix:
- Avocado oil is nourishing and penetrating, but it becomes sticky when massaged into a large area.
- Calendula oil is made by mascerating calendula petals. It is beneficial in any cosmetic preparation for chapped or cracked skin.
- Carrot oil is rejuvenating and particularly good for a neck massage. It is rich in vitamins and a good tonic.
- Evening Primrose oil is useful for scaly skin and dandruff.
- Wheatgerm oil is nourishing and rich in vitamin E, but is rather “oily” on its own. It is a natural antioxidant (preservative), and a teaspoonful added to 2 fluid ounces of massage oil will extend its keeping time.
A typical distillation aparatus, or still, is set up. This apparatus consists of the following:
- a flask in which the herb is placed and covered with water;
- a condenser to condense the vapors back into the liquid;
- a receiver to collect the liquid condensate.
Heat is applied to the flask, and the water and herb is boiled. This drives out the volatile oils as vapor. The condenser consists of a coil through which the heated vapors pass, and a water jacket through which cold water runs to cool down the vapors so that they return to a liquid state and can be collected in a receiving vessel. The cold water comes from the tap through a hose which is attached to the lower nipple of the condenser. This water, now warmed by the heat of the gases traveling through the coil, exits via the upper nipple through another tube and out the drain. The steam and volatile oil vapors condense together and are collected in the receiver, where they separate, usually with the oil floating on the surface of the water.
For collecting small quantities of volatile oil, or for measuring volatile oil content of an herb, a special receiver, called a Clevinger apparatus, is used. This device has a scale graduated in milliliters on which the oil can be measured. It also has a stopcock or spigot at the bottom through which the water can be drained and discarded, leaving the oil to be collected.
A laboratory stand with a clamp makes certain that the apparatus on the counter is stable. It is also wise to make sure that all the joints are clamped together with little plastic clamps so that a sudden movement or an accidental brush will not separate the equipment in the middle of the process. Initial equipment will likely have 20/40 joints, and clamps should be ordered to fit that size. For larger quantities, a separator funnel can be used to separate the water and oil.
Occasionally the unexpected happens. Sometimes, the oil and water emulsifie or the mixture foams. There are methods of returning them to the proper state, as using boiling beads or adding saline. These are tricks that phytochemists have already learned, and the ones to whom one turns when a problem arises.
This is a simpler method of extraction and used for oils that are extremely heat sensitive. Simply coat a glass pan with a thin layer of pure lipids, usually lard or rendered fat, then add a layer of fragrant flowers. Leave them for 24-36 hours in a warm place and replace them with a fresh batch of flowers, scraping the fragrant fat into a container.
If using the animal fat is undesirable, fill a pint jar with flowers, add almond oil to cover, and top with a cheesecloth cover. Let sit for a couple of days. Press out the flowers, add new ones, and repeat until the scent is as strong as desired. This may take three or four batches of flowers. This is a good method for making massage oil and will not give a pure oil as distillation would, but it does in a pinch.
- 5-10 drops essential oil
- 20 ml (1 tablespoon) carrier oil
This amount is adequate to massage the body. One full body massage generally only requires about 2-4 teaspoons of a blend. Essential oils quickly deteriorate. Therefore, mixtures should be prepared only as needed.