Essential oils intended for aromatherapy massage need to be diluted in a natural base oil such as olive, almond or sunflower seed - preferably labeled 'unrefined' or 'cold pressed'.

If a vegetable oil is not labeled as such, it is certain to be a highly refined product extracted by high pressure, intense heat and possibly petroleum derived solvents. Moreover, the oil will also have been bleached, deodorized and artificially colored. The devitalized end product may then receive a dose of synthetic vitamins to replace those, which were destroyed during the refining process. To add insult to injury, it is quite legal to describe such a product as 'pure'.

While a refined base oil will not harm the skin (unless you have an allergy to the plant from which it derives), unrefined oils are far superior.

Indeed, they are health treatments in themselves. The oils contain naturally occurring nutrients such as vitamins D and E, essential fatty acids and trace minerals such as calcium and magnesium, all of which are highly beneficial to the skin whether taken internally or used topically. For many years aromatherapists have promoted refined oils such as grapeseed and soya (unavailable in an unrefined state) on the grounds that they have almost no odor of their own and therefore do not interfere with the aromas of essential oils. The fruity-peppery aroma of extra virgin olive oil blends especially well with citrus essences; and while unrefined almond oil is a good base for all essential oils, its dulcet aroma marries exceptionally well with rose and chamomile.

Aromatherapists are somewhat divided over the issue of refined base oils - some believe they are ideal for aromatherapy treatments, some would argue otherwise. Most choose to compromise by mixing a refined oil such as grapeseed with a smaller percentage of an unrefined oil such as avocado, olive or jojoba. 

However, there is consensus of opinion regarding mineral oil: it should never be used as a base for essential oils.

Mineral oil (often available as 'baby oil') is derived from petroleum. Not only does it lack the health-giving properties of unrefined vegetable oil, according to some health experts mineral oil applied to the skin (or taken by mouth) makes fat-soluble nutrients leach from the body.

It also tends to clog the pores of the skin, contributing to the development of blackheads and pimples.

Also, when used as a base for essential oils, it hinders their absorption through the skin.

Above all, the use of synthetic oil of any nature runs counter to the philosophy of aromatherapy.