Essential oils can be quite expensive to buy so I though I would cover how you can make many of them at home.
Firstly, what is an essential oil? The formal definition for essential oil is that it is a concentrated hydrophobic liquid that contains volatile aromatic compounds from flowers and plants. In pure layman's terms it's the concentrated smelly stuff from flowers!
Most essential oils are made commercially by distillation. In this process the raw plant material, which can be in the form of flowers, bark, leaves, stems, roots or seeds, is placed on a rack above the water in a still. When the water is heated, the steam passes through the flowers vaporizing the complex volatile compounds. These vapors then pass through a cooling coil and condense back into liquid form. The essential oil itself then forms a film on the top of the liquid. It is then separated by skimming. The remaining water underneath the oil is a product known as a hydrosol and is often sold in this form as rose water or lavender water.
Unless you live in West Virginia and have a cousin with a still this probably isn't a practical method to use at home. Luckily distillation is a fairly modern method of producing essential oils so we have some more traditional alternatives for making our own fragrance oils.
Enfleurage is the process of placing flower petals or similar plant material onto trays of odourless vegetable oils which will absorb the flower's volatile essential oils. You can use a variation of the technique to make your own essential oils. Although this doesn't produce oils as concentrated as you can purchase, this is fairly easy to do at home given the raw materials.
You can use a variety of vegetable oils in this process including olive oil, sweet almond oil or refined jojoba oil.
How to make essential oils:
You will need:
Half a cup of oil
Four cups of tightly packed flowers (see instructions)
A wide-mouth jar such as a mason jar
A wooden mallet or similar
A zipping plastic bag
Some cheesecloth for filtering
You will need four cups of flowers picked over the course of a week for the best results.
Put one cup of the flowers into the plastic bag and expel as much of the air as you can before sealing. Bruise the flowers in the bag with a wooden mallet. The idea behind putting them in a plastic bag first to cut down on the mess and to avoid losing any of the material. Don't bash them to a pulp, this isn't necessary, just hit the bag a dozen times gently.
Mix the flower material with the oil well and place it into the jar. Seal the jar and put it into a warm place for about 48 hours. A sunny window ledge or a warm spot in the kitchen is fine. The warmer the spot, the less time they need to be left but don't overdo the warming or you may damage the oils.
Filter the mixture through the cheesecloth and return the oil to the jar. Discard the filtered flower material.
Take the next cup of flowers and repeat the bruising process. Mix this batch with the oil from step one and leave in a warm place for another 48 hours or so.
Repeat twice more with the next two cups of flowers.
After the final straining, transfer the oil to a storage bottle and keep in a cool, dark place. Colored bottles are ideal for storage. This will keep for up to a year.
This whole process to make your own essential oil will take a week or so so isn't as quick as the distillation process but of course doesn't involve the expense of building or buying a still.