Fixed oils vs Macerated oils
Carrier oils also known as fixed oils are used in greater proportions in an aromatherapy treatment than essential oils, so it is important to understand their properties and benefits. A carrier oil is used to help carry the essential oils into the skin as their molecules are bigger they cannot penetrate further than the dermis but the essential oils are smaller and go into our bloodstream. It would be dangerous to use just pure essential oil neat onto a person so the carrier is there to dilute them down and also help them mix as essential oils like fats. As an aromatherapist I like to be as choosy about my carrier as I am about my essential oils.
The penetration of the skin by carrier oils is variable and depends on many physiochemical properties such as the degree of saturation and viscosity. Some are thicker than othes. However, many carrier oils contain vitamins and other smaller components that can be absorbed by the top layers of the skin to enhance appearance and skin health. Sometimes there is the option of macerated oil but what really is that and how is it different?
All carrier oils are made from glycerol and a selection of fatty acids and the molecules are formed into long chains of varying length, depending on the oil. Clearly, these are heavy molecules but some of the oil penetrates your skin via pores, hair follicles and sebaceous glands, and also on occasion via ingestion. In fact, aromatherapy quality vegetable oils are by far the best in terms of health-giving nutrition than any of the refined commercial oils they just cannot stand the heat but make great options for salad dressings.
Fixed oils are usually produced by cold pressing from nuts or seeds, though this is slightly misleading as a certain amount of heat is used during extraction (40oC – 60oC). The nuts or seeds are placed in a horizontal press with an electronic screw. As the screw turns the oil is squeezed out into a trough below. Refined carrier oils have often had a chemical process on them that changes the colour, odour and sometimes properties but has a longer shelf life. Cold-pressed carrier oils are more expensive, but they are the only real option to be used on your skin as they are 100% natural.
Examples of carrier oils that are fixed are Sweet Almond, Sunflower, Grapeseed, Linseed, Apricot Kernel, Jojoba and anything else from a nut or seed.
The verb to macerate comes from Latin macerat- ‘made soft, soaked’. It todays terms it is to make soft by steeping in a liquid. The maceration process is a way to incorporate specific plant properties into a fixed oil using raw materials such as flowers or leaves. This raw material is picked and chopped up which breaks the plant cells releasing the lipophilic molecules (including essential oil compounds). This material is put into a base fixed carrier oil and then put in a warm place (traditionally sunny) and frequently stirred for up to three weeks. The resulting carrier oil, now known as a macerate, is then strained off and filtered. The oil soluable elements from the plant material including colour and essential oil compounds are now in the fixed oil base and have created a ready blended massage oil.
Carrier oils that are macerated are Calendula, Hypericum, Carrot, Arnica, Echinacea and anything else that is created using flowers, buds, leaves or fruit