Essential Oils – Frequently Asked Questions - Wholesale Supplies Plus

Essential Oils – Frequently Asked Questions

This article answers commonly asked questions regarding Essential Oils, how they are processed and how they are used.

Essential Oils – General Questions

What are essential oils?
Essential oils are the naturally occurring oils derived from plants. They can be obtained by steam distillation or cold pressing (expression), and have the characteristic aroma of the portion of the plant from which they were derived. These 100% pure oils are "neat", meaning they have not been processed, diluted or manipulated in any way with solvents or other additives. Because they are naturally occuring, the particular species of plant harvested and distilled for its essential oil during one time frame in one region may produce a fragrance that differs from the same species grown in a different region, or in the same region at a different time. Also, because essential oils are pure, undiluted naturals, people can experience allergies to essential oils when they are sensitive to the plants from which they are derived.

How are essential oils produced?
Pure essential oils can be produced using either distillation or expression. The production method depends on the natural plant material being processed. For example, citrus oils are commonly cold pressed ("expressed"), while steam distillation is used for most herbs.

How does steam distillation work?
In steam distillation, the plant material (such as the flowers, leaves, wood, bark, roots, seeds or peel) is placed in a tank and steam is introduced into the bottom of the tank. The steam passes through the plant material, extracting volatile (good) componds. The vapors then flow through a coil where they condense back to a liquid, which is collected in a receiving vessel. This condensed liquid is then separated pure essential oil and distilled plant water.

At this point, the pure essential oil can be packaged for sale or further processed with processes such as "redistilling". 

The distilled plant water is referred to as a hydrosol, hydrolat, herbal distillate or plant water essence, which may be sold as another fragrant product. Popular hydrosols include rose water, lavender water, orange flower/blossom water, lemon balm water and clary sage water. Some plant hydrosols have an unpleasant scent, and are therefore not sold.

What is redistillation?
Some pure essential oils may go through additional distillations to separate out specific aromatic fractions. Each additional distillation (aka "redistillation") of a pure essential oil can produce a significantly different aroma. For instance, Wholesale Supplies Plus regular Crafter's Choice Peppermint Essential Oil smells more like peppermint tea or a peppermint plant, while the Crafter's Choice Redistilled Peppermint Essential Oil smells a lot like peppermint candy canes!!

What are concretes, resins and absolutes?
These are natural aromatics that are solvent extracted, rather than distilled or expressed. Most flowers contain too little volatile oil to undergo expression and their chemical components are too delicate to withstand the high heat used in steam distillation. So, alternate methods of extraction need to be used - such as the solvents hexane and supercritical carbon oxide.

What is a concentrate?
Extracts from hexane and other hydrophobic solvent are called concentrates. They are a mixture of essential oil, waxes, resins, and other oil soluble (lipophilic) plant material. Concentrates are highly fragrant, but contain large quantities of non-fragrant waxes and resins as well.

What are absolutes?
Absolutes are highly concentrated, thick liquids derived from concentrates or resins. Traditionally, absolutes are prepared by dissolving concentrates in ethanol or another solvent, such as ethyl alcohol, which dissolve the fragrant low-molecular weight compounds. The alcohol is then removed in a second distillation. So, all you are left with at the end is the absolute.

What are resins?
Resins are hydrocarbon secretions of many trees, particularly coniferous trees. They are valued for their concentrated properties; for instance, some of them have been found to have antibacterial and wound healing properties. Since there are different extraction methods, it is important to follow the vendor's guidelines for proper usage of any resin you might purchase.

What is supercritical carbon dioxide extraction?
One of the newer extraction methods is supercritical carbon dioxide - also used to make decaffeinated coffee. It has the advantage of not leaving petrochemical residues in the product and preserving the very fine top notes which steam distillation usually destroys. While supercritical carbon dioxide does not directly yield an absolute, it will extract both the waxes and the essential oils which make up a concrete. Then this result undergoes further processing with liquid carbon dioxide, to separate the waxes from the essential oils without decomposing (or denaturing) the compounds. When this is done, the pressure is reduced, reverting the carbon dioxide back to a gas. No residue from the process is left in the resulting waxes and essential oils.

What can I mix essential oils with?
Essential oils are usually lipophilic compounds - which means that they are "oil-loving" and don't blend directly with water. However, they can be diluted in solvents like pure ethanol (alcohol) and oil, and added to a variety of media like lotions, soaps and sprays. Wholesale Supplies Plus sells a fragrance/essential oil modifier which is a proprietary emulsifying agent that allows oil to dissolve with water. When used correctly, your end product will remain 100% clear. To use it, you thoroughly mix 4 parts FO Modifier to 1 part oil based EO. This creates a new, modified essential oil that will easily incorporate into water. You can add 1% of the modified essential oil to water based products.

Are there any cautions to using essential oils?
Yes - essential oils are highly concentrated and should be stored in amber glass bottles. The International Fragrance Association has recommended guidelines for the maximum use level for skin exposure. It is essential you follow these recommendations as they have been developed based on concrete scientific data. You will find that some essential oils can be used be used directly on the skin and others can only be used at 0.5%. 

Some essential oils are photosensitizers, which increase the skin's vulnerability to sunlight. It's especially important to take care in using those in products which may be used on skin exposed to the sun, like lip balms and lotions.

Can Pure Essential Oils be used in candles?
Wholesale Supplies Plus does not recommend using essential oils in candles. Testing has shown that some pure essentials oils can be unpredictable when exposed to the flame of a candle and in some instances the essential oil can over time concentrate in the melt pool resulting in fire. If you choose to use pure essential oils in a candle, you must test several batches of candles with different burn testing to ensure there will not be a problem with consumer usage. If you wish to use essential oils in a candle, we recommend the Crafter's Choice Essential Oil Blends which have all been pre-market tested for candle performance.

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