Diffusers, either the electric or candle variety, heat the essential oil until it evaporates into a mist or fog, dispersing the aroma into the air. Also available are ceramic rings that fit around light bulbs. They have an indentation to hold a few drops of oil which heats up with the light bulb and diffuses into the air. If a sensitivity to an oil occurs it is generally due to full strength application onto sensitive skin . Dilution in a carrier oil not only protects you from a reaction, it spreads the oil over a larger area and so stimulates a greater response.
Essential oils tend to increase circulation at the surface of the skin, opening up the pores.
This is the key to overall absorption, and consequently to the overall health of the skin. Of the pure vegetable oils available to use for this dilution, jojoba is the heaviest, almost a liquid wax, and grape seed oil is the lightest. Sweet almond oil is the best all purpose carrier oil, and apricot kernel, also very light, is easily absorbed by mature or damaged skin. Massage therapists report wonderful results with grape seed oil because it is so thin, glides easily, and is completely absorbed. To use an essential oil on a small, specific site mix a drop into each application of a scrub, mask, pack, or cream.