Essential oils differ from other types of oil in that they are lighter than water. They also evaporate quickly when they come in contact with air unlike other oils and when dropped onto paper, do not leave an oily mark/spot on it.
It takes less than 20 minutes for essential oils to penetrate the skin. After skin penetration, essential oils get into the fatty parts of the skin and then on to different layers, finally reaching the blood stream. It takes anything between 20 – 70 minutes for essential oils to reach the bloodstream, so it must take less than 20 minutes to penetrate through the skin.
The three types of essential oils in terms of evaporation rates are: top note oils, middle note oils and base note oils.
Top Note Oils: These are the fastest acting essential oils and the lightest. They are uplifting and stimulating in nature and affect conditions of mental exhaustion and disinterest, apathy, etc. These oils are effective for a period of 24 hours. Examples are lemon and eucalyptus oils, basil oil, bergamot oil, Clary sage oil, and eucalyptus oil
Middle Note Oils: These oils are neither too heavy nor too light and absorb semi-easily. They are used most commonly and affect many functions of the body including digestion and metabolism, etc. They are balancing in nature. These are effective for approximately four days after application. In the middle note oils, marjoram oil is the most versatile and addresses the widest range of conditions. Other examples are chamomile oil, lavender oil, cardamom oil, marjoram oil and oils of most spices and herbs.
Base Note Oils: These oils are heavy and are used in the management of chronic conditions, so they are often used on elderly people. They act on mucus membranes and these oils belong to cellular and vegetable domain which influences the quality of tissue. These are effective for approximately seven days after application. Examples are rose oil, cedar wood oil, jasmine oil, and sandalwood oil.