Read Mixing Essential Oils for Magic: Aromatic Alchemy for Personal Blends for Free Online

For example, heat converts the chemical matricin in German chamomile to chamazulene, which gives the oil its blue color. Medicinally, this is considered advantageous because the chamazulene makes the oil useful for anti-inflammatory treatments. On the other hand, jasmine flowers are so delicate that heat or water destroys the volatile oil.
    To avoid the negative effects that heat or water have on some plants, the solvent extraction process is used to obtain essential oil. Chemicals such as butane, hexane, ethanol, methanol, or petroleum ether are used in this process to rinse the volatile oil from the plant. This rinsing produces a semi-solid, waxy product called a concrete which, in addition to the volatile oil, contains the plant’s waxes and fatty acids. In the case of jasmine, the concrete is 50% wax and 50% volatile oil. An advantage of a concrete is that it is more stable and concentrated than an essential oil.
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    Further rinsing with alcohol or ethanol, or a freezing process is used to remove the solvents and waxes. This step produces a substance called an absolute. While these substances are usually viscous liquids, they can be solids or semi-solids. Absolutes are highly concentrated and have a stronger, richer fragrance that is often more like the plant itself than the essential oil, which makes them attractive for perfumery. The solvent extraction method produces a greater yield than distillation and is useful on plants that generally have low quantities of oil. Absolutes and concretes are sometimes distilled to produce an essential oil. A problem with absolutes and concretes is that they contain impurities: traces of the chemicals used to remove the oil from the plant material.
    In an attempt to avoid the problem of impurities, a newer method called CO2 ex-
    traction, sometimes called super-critical CO2 extraction has been developed. This process uses carbon dioxide in a liquid state at high pressure to dissolve plant material and release the oil. Afterwards, when the pressure is reduced, the carbon dioxide returns to its gas-eous state leaving the oil behind and reportedly no chemical residue as in typical solvent extraction. However, like solvent extraction, CO2 extracts contain fats, waxes, and resins from the plants.
    There are two types of CO2 extraction products that you may encounter. One is cre-
    ated at lower pressure and designated as a select extract or SE. It has a liquid consistency and does not contain as much of the plant fat, waxes, and resins. The other type is called a total extract. It is thicker than the select and contains more of the non-soluble plant material. According to Ingrid Martin, author and instructor of aromatherapy at Ashmead College in Seattle, Washington, lab tests show “significant differences in chemical compositions” between true essential oils and the CO2 products.13 In addition, I have not found information on experiments to determine if they produce auras as pure essential oils do.
    Another substance created by standard solvent extraction is called a resinoid. As the name implies, it comes from resinous plant materials, which include resins, balsams, oleoresins, and oleo gum resins. (Refer to the Glossary for information on these substances.) The resinoid end product can be in the form of a viscous liquid, a solid, or semi-solid. A resin absolute is created by a further extraction process using alcohol. Instead of solvent extraction, a few resins such as frankincense and myrrh are actually steam distilled to create essential oils.
    13. Martin, Aromatherapy for Massage Practitioners , 13
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    Another method of extraction is called enfleurage . This is not commonly used today because it is extremely time-consuming and labor intensive, thus making it costly. This process is used to create an absolute from expensive flowers such as jasmine. Instead of extracting the flower essence with a chemical solvent, a fatty substance such as tallow or