If you, like many others, are trying to make the switch from synthetic fragrance to natural fragrance in your life and home, it's helpful to understand what falls into the natural fragrance category: essential oils, absolutes, concretes, and CO2 extracts. While synthetic fragrances are derived from laboratory chemicals, these natural ingredients are made from raw plant materials. Synthetic fragrance often has hundreds of undisclosed ingredients, including petrochemicals, mystery allergens, and phthalates. With natural fragrance ingredients, what you see is what you get, like "lavender essential oil". Synthetic fragrance tends to smell the same on everyone, for hours and hours on end. (Have you ever tried to wash the smell of Tide out of clothing? Impossible. What about when your friend hugs you with her favorite perfume on, and you smell it on yourself for the rest of the day? No fun.) Natural fragrance smells different on everyone, and it changes and fades over time, just like the plants themselves. Best of all, the more you know about the beautiful processes that go into making these natural fragrance ingredients, the more you'll find them to be irresistibly romantic and alluring. Who wants to spray on a mass-manufactured chemical when you could dab on an oil made from the petals of thousands of roses collected by careful Bulgarian hands in the pre-dawn light?
For years, understanding the differences among these natural fragrance ingredients was a bit like understanding football for me. Someone could explain it fully, I would get it (mostly) in that moment, and then it would become really foggy in my memory afterwards. (Me: "Wait, what's a first down again?") Now that I have been working intimately with these materials for many years, I finally understand them. I'll do my best to explain them all to you.
The most straightforward category in this aromatic group is the essential oils. There are several ways to make essential oils, the most common of which is steam distillation. This means that steam is passed through a hopper (like a steaming basket in your kitchen) containing raw plant material, causing the plants to release the aromatic compounds stored in their leaves or flowers, which rise with the steam into a cooling system. As the combined steam and plant compounds are cooled in another tube or chamber, they separate into water and oil. The water contains the water-soluble (hydrophilic) parts of the plant, which is why the remaining water is called a floral water or a hydrosol.
Hydrosols are used frequently in skin care. They are very mild, and have gentle benefits to the skin. A properly made hydrosol is sterile - as it undergoes distillation, a process where the liquid is turned to gas and then liquid again—all organisms are left behind. Hydrosols make excellent skin toners, or can become part of the water phase of a cream or lotion.
The oil-soluble aromatic compounds rise to the top of the hydrosol in a separate layer, which can be decanted off, and is then called the essential oil of that plant. Essential oils have been used for centuries in aromatherapy, perfumery, medicine, and skin care.
This same procedure is used in hydro-distillation, where the plant material is actually submerged in water, and in hydro-diffusion, where steam is forced in from the top, rather than passed through the plants from below. Not all botanicals can withstand this high-heat method of extracting essentials oils, which is why other methods exist.
Citrus essential oils, for example, are more commonly obtained by expression (also known as cold-pressed or expeller-pressed, the former being a temperature-controlled process). This means that the peels are first pricked all over to puncture the cells containing the oils, soaked in warm water, and then mechanically pressed to squeeze out the essential oil. Certain citrus peels are obtained in bulk as a byproduct of the citrus juice industry, which is why many of these essential oils (lemon, orange) are readily available and less expensive than things like geranium or lavender.
So, that covers the term "essential oil". I hope you're still with me, because that was the easy part.
The rest of the aromatics are obtained using solvents: hexane, dimethyl ether, or supercritical carbon dioxide. Previously, benzene was used as a solvent in the fragrance industry. We are glad it is no longer used for two reasons—first, it is carcinogenic (cancer-causing) and, second, it leaves a fairly high residue in the final product. With hexane and ether, the residue is typically less than 10 ppm (parts per million), which is fairly negligible. The least toxic of these solvents is carbon dioxide (CO2)—you know, the stuff you just exhaled.
In this method, which is steadily gaining popularity, carbon dioxide is placed in a chamber with raw plant material. The chamber is then put under extreme pressure (100 to 200 times normal atmospheric pressure), at approximately 85 degrees Fahrenheit, and this combination of mildly increased temperature and hugely increased pressure puts the CO2 into a “supercritical” state. This is an uber-geeky concept, but basically it is a condition where the CO2 is part liquid, and part gas (like a dense fog), and allows the aromatic components of the plant to dissolve in the CO2 fog stuff. The supercritical CO2, which now contains the extracted aromatic compounds, is separated from the remaining raw plant material, and then returned to normal atmospheric pressure, where carbon dioxide can only exist as a gas. When the CO2 changes back to gas, it leaves behind ONLY the extracted aromatic part of the plant. There is literally ZERO residue of the solvent in the remaining CO2 extract, because it has changed physically from a supercritical state to a pure gas. Such a cool trick, right? One of my favorite CO2 extracts is our organic rosemary antioxidant, which we add to your oils and soaps to keep them from going rancid before you've had time to enjoy them. Another cool trick.
CONCRETES & ABSOLUTES
These are the more traditional fragrance compounds that have been used in the world of perfumery for many years. Long ago, people used a technique called enfleurage to extract scent from flowers like jasmine and rose—flower parts were combined with animal fat and pressed between pieces of glass.
After a few days, the flowers were removed, and replaced with fresh flowers—this process was repeated for several rounds until the fat was full of the desired aroma. This technique is used much less frequently now, as most people do not want their personal care products to be derived from killing animals. In most instances, concretes and absolutes have taken the place of enfleurage.
A concrete is made by combining plant materials, a solvent (hexane, a liquid, or ether, a gas) and natural waxes or resins. Once combined, the solvent is removed by gentle heating in a vacuum (negative pressure environment, not a Hoover) and reused. The remaining waxy compound is the concrete. It comprises wax, resins, and other high molecular weight (heavy) botanical components, as well as the low molecular weight (light) aromatic compounds.
Once you have a concrete, you can make an absolute. The concrete gets washed with ethyl alcohol, which takes with it the light aromatics from the concrete. The ethyl alcohol mixture is then distilled again, which removes almost all of the alcohol (>95%), leaving behind the extracted aromatic compounds in the form of an absolute. Modern natural perfumery uses absolutes for things like jasmine, rose, and orange blossom, as they can't withstand the process of steam distillation.
Natural Fragrance Notes
- On a label, natural fragrances can be listed several ways, such as "lavender essential oil", "rosemary CO2 extract", "lavender extract", or "essential oil blend". (We have started listing every single essential oil we use on every label, so you know exactly what's in your products.) When you see "plant-derived fragrance" or "plant-based aroma", you might email the company to ask what that entails. A company with nothing to hide will gladly respond!
- Often you will see essential oil isolates, such as geraniol, limonene, and linalool, on a natural product label. These isolated fragments of essential oils are obtained by distilling an essential oil itself, separating it into different "fractions" based on boiling points. They are considered natural. While they contribute to a product's scent, they are usually employed as part of the product's preservation system more than the aroma itself.
- Most essential oils are too acidic to be applied directly to the skin. One exception is lavender essential oil, one of the more well-studied essential oils. There is evidence to support the use of lavender essential oil as an analgesic (pain-reliever), anti-inflammatory, anxiolytic (decreases anxiety), and topical antibiotic. Applied to a fresh burn, lavender essential oil can alleviate discomfort and decrease the inflammatory response.
- Another essential oil with increasingly documented efficacy is thyme—it is the active ingredient in many natural hand sanitizers and wipes, capable of killing most common microbes. My favorite hand sanitizer is the CleanWell foam.
- Use caution with citrus oils in skin care—a somewhat alarming rash called a phototoxicity reaction (or phytophotodermatitis) can occur when certain citrus oils on the skin are exposed to sunlight. Grapefruit, lime, bergamot, lemon, and bitter orange are the most likely to cause a phototoxic reaction, while sweet orange and bergaptene-free bergamot essential oil are safer. Also, distilled citrus oils, rather than expressed citrus oils, have a lower incidence of phototoxicity.
- Just because you're using natural fragrance doesn't mean you can't have a reaction to it. I have seen people with allergies to lavender, geranium, and chamomile, but you can be allergic to almost anything, so be aware of which oils you're using. Also, make sure you're using essential oils in the proper dilution and locations - some essential oils (peppermint!) should never be used on your face or near your eyes, and very few should go on the skin right out of the bottle.
Got questions? Ask away!!
With love and aromatic education from us to you,