How to Make Essential Oils

Essential oils are highly concentrated, volatile oils that can be extracted from aromatic plants. Their use dates back to ancient times, and their wide variety of therapeutic, medicinal and culinary uses has ensured their continued popularity.

About 700 different kinds of plants contain useful essential oils, and there are several methods employed to extract them, the most common of which is distillation

While essential oils can be very expensive to buy, they are relatively cheap to distill at home. This guide provides basic instructions on how to extract the oils using the relatively simple and effective water-and-steam distillation process.

Steps

Obtain or build a still (the apparatus used for distilling). You can purchase one specially designed for distilling essential oils; these generally cost a couple hundred dollars or more, but if you plan on doing a lot of distilling and you're not particularly mechanically inclined, this is probably the way to go. If you want to try building a still, you've got plenty of room for creativity - there are thousands of still designs, and even today, many stills are homemade. The key components of a still are:
- The heat source or furnace, which is used to boil the water. Direct fire, a fire built under the retort is the oldest method for heating the still. Today, we can also use gas, such as propane or butane, and electricity. Fuel costs are a major factor when considering a heat source for you distiller;
- The holding tank or retort, which holds both the water and, just above the water on a grate or false bottom - picture a vegetable steamer - the plant material to be distilled;
- The condenser, which collects the steam and cools it, usually by piping it through a tube immersed in cold water, and...
- The separator, which separates the essential oil from the water vapor. The separator, or Essencier, is one of the most important pieces of apparatus a distiller can have. This enables the distiller to separate the essential oils from the distillate in a passive manner.
Harvest your raw material. The quantity of essential oils contained in a plant varies over the course of the plant's development, so it is essential to harvest at the right time. This will depend on the type of plant, so you need to do some research to determine when to harvest.
It is also critical to harvest the plants correctly - careless handling, harvesting the wrong parts, even harvesting at the wrong time of day can reduce the quantity and quality of the essential oils. Again, research the plant you wish to distill.
If you're buying harvested material, you don't have much control over the harvesting process; look for plants that appear healthy and undamaged, and ask the seller when they were harvested. Generally plants that are in whole form (not crushed or powdered) are best.
Dry the plant material. Drying reduces the amount of oil in each plant, but can greatly increase your yield per batch because you will be able to fit more material into each batch. Drying should be done slowly and NOT in direct sunlight. You can choose not to dry your plant material. Commercially grown plants such as lavender and peppermint may be allowed to dry in the field after cutting for a day or so. The ideal drying method varies from plant to plant, but in general you should not overheat the plants - drying in the shade or even in a dark room minimizes the oil lost - you should not over-dry them, and you must not allow the plants to become wet again before distillation. Distill as soon as possible after drying.
Add water to the tank of your still. Use clean water, ideally filtered or distilled and as soft as possible. If you're using a manufactured still, follow the manufacturer's direction. Otherwise, simply make sure you have enough water in the still to complete the distillation; depending on the plant and on the quantity, distillation can take anywhere from a half-hour to six hours or more after the water boils.
Be sure that the water level is close to, but not touching, the false bottom that will hold the plant material.
If you are performing a hydrodistillation (this is useful for delicate flowers or powdered roots, bark or wood), you will need to have your plant material free floating IN the water.
Add your plant material and pack it tightly in the still. You do not need to chop or cut the plant material, and doing so will cause you to lose some of the oils. The plant material should rest on the false bottom or grate above the water and should touch the sides of the still as little as possible. The layer of plant material can be quite thick as long as it is below the steam outlet (a couple inches below the outlet for a small still, a foot below for a large one).
Close the still and boil the water. Most plants will release their essential oils at 100 degrees Celsius or 212 degrees Fahrenheit, the normal boiling point of water.
Keep an eye on the still. After a while the distillate should begin to come through your condenser and into your separator. The process should be fairly hands-off, but you will want to ensure that you do not run out of water in your still. Depending on the length of the distillation process, you may also need to change the water in the condenser so that the cooling process continues to work. Follow the instructions for the particular plant you are distilling.
Filter the collected oil (optional). Once your distillation is complete you may filter the oil through cheesecloth or similar dry cotton fabric. Ensure that the cloth is dry and clean - detergent residues as well as dirt can contaminate the oil.

Pour the oil into a container for storage. Do this as quickly as possible. Most essential oils can be kept for at least two years, but some have extraordinary shelf lives. To maximize the useful life of your oil, keep it in a dark glass bottle or stainless steel container. Use a clean funnel to pour the oil into the container, and make sure the container is impeccably clean before pouring the oil into it. Store in a cool, dark place.
Decide what to do with the hydrosol. The distillation process produces the essential oil and a hydrosol, the term for the water that has been distilled and which collects in the separator. Some hydrosols are usable themselves - rose water or lavender water, for example. If you do not wish to save the hydrosol you can pour it into the still for the next batch (if you will be distilling another batch immediately) or you can discard it.
You can also place plant material directly into the water. This method is easier, but the quantity and quality of the resulting oil will be reduced. The best distillation method is steam distillation, in which the water is boiled in a separate retort and then pumped into the retort which holds the plant material. This method makes the best quality oil and allows you to control the process better, but it is more complicated (and more expensive) to set up.
Percent yields vary from plant to plant. You will need a lot of plant material to make a little essential oil. You may just decide to make hydrosols. If that is the case a small distiller such as a 5 liter or 10 liter copper distiller will be adequate. If you plan to make essential oils, consider obtaining a larger apparatus. A 40 liter rotating column alembic distiller, for example, will enable you to make up to 5 ounces of essential oil and a large quantity of hydrosols.
Most essential oils are held in the plant's oil glands, veins and hairs, and these are very fragile. If you disturb or break them, you will reduce your yield of oil, so it is essential to handle the plants with care and to handle them as little as possible.

Stainless steel and glass are the best materials for your distillation components. Do not use plastic tubing. Copper pots are traditionally used for the retort, and these work well for a variety of plants, but some plants contain chemicals that react with copper to produce unwanted impurities - heavily tinned copper is suitable in all cases, however. Aluminum can also be used, but not with plants, such as wintergreen and cloves, the oils of which contain phenols.
While distillation removes many impurities, pesticides and herbicides can contaminate your oil. For this reason it is best to use organically grown plants, whether you purchase them or grow your own.
Essential oils are extremely concentrated, and it is often advisable to dilute them in a carrier oil before applying them to skin.
The most popular carrier oils are almond oil and grapeseed oil, but a variety of different oils can be used. They can be added during the bottling process or mixed with the pure oil just prior to use. The latter is often preferable because you may not want diluted oil for some uses, and carrier oils often have a shorter shelf life than essential oils.

Warnings

Organic does not mean that pesticides or fertilizers were not applied to the plant, just different from commonly used synthetic pesticides or fertilizers (which some are less toxic than types of organics). Try to find a local grower who can inform you about how the plant was grown.
Most essential oils should not be ingested, especially if undiluted, and many should be diluted even when applied topically. Also, some essential oils are toxic. See the external links for more information.
For the distillation of most flowers, skip the drying process and distill soon after harvesting.
When drying plant material, exercise care not to allow the material to become contaminated with dirt, dust or other contaminants. Contamination will reduce the quality of your oil and may make it unusable.
Do not distill a batch for too long (check recommendations for the specific plant), as this will add little additional oil but may possibly contaminate your batch with unwanted chemical compounds.

Things You'll Need

Distillation equipment, including at least a tank or retort, a condenser, a furnace or other heat source and a separator.
Glass tubing to connect distillation components
Plant materials from which to extract the oils
Containers made of dark glass or stainless steel in which to store the oils