Originally published on Guide to Aromatherapy
The type of essential oil diffuser you need depends on the application you have in mind. There are various types on the market, but not all types are suitable for all purposes. Basically there are four kinds: the type that uses a votive candle/tea light to heat the oil mixture, the type that uses electricity, the type that uses an existing heat source and finally what you might call a scent diffuser, which uses no heat at all, relying on evaporation as a diffusion mechanism.
The reed diffuser (or stick diffuser)
The type which relies on evaporation is not usually used for therapy, which is why I referred to it previously as a scent diffuser – it carries on releasing fragrance into the area in which it is placed 24/7 from the time it is set up until it runs out of liquid. This liquid contains about a quarter to a third by volume of dilute essential oil mixed with dipropylene glycol, with perhaps some preservative added.
This type of diffuser is used purely to provide an ambient fragrance, whether in general living areas or bathrooms and similar places. Though it is possible to make your own reed diffuser by purchasing the various materials, in most cases, reed diffusers are sold as a package, with the fragrance you select at the time of purchase and all the other required ingredients so that you can assemble it at home when you wish to start using it.
To prepare your reed diffuser for use, pour the liquid into the container provided, leaving a good space at the top to allow it to rise when you insert the sticks. Then insert the sticks one or two at a time until they are all in place. If you have any liquid left over, make sure to seal the bottle tightly and put it somewhere cool and out of the sun, so that you can refresh the diffuser as required.
The oil burner
The essential oil “burner” will be familiar to most people. They come in an amazing variety of shapes and sizes, ranging from the very simple to the highly ornate. Despite the name, the flame (usually provided by a votive candle or tea light) never comes into contact with the essential oil, which is usually mixed with water in a container positioned above the candle, so the oil is not burnt at all, but merely heated sufficiently to become volatile and disperse into the air.
When used as room fragrance, some people use crystals as a medium instead of water. These can be purchased already impregnated with scent, but it’s unlikely you will find therapeutic quality essential oil sold in this way.
Oil burners are also sometimes called oil warmers, which is a more accurate description.
The electric oil diffuser/electric oil warmer
Available in both mains operated and battery operated types, electric oil diffusers work in a similar way to oil burners, but using electricity as a source of heat. They are suitable for use in situations where a naked flame might be dangerous or not permitted for health and safety reasons.
You can also get a car diffuser which runs off the lighter socket.
This type of diffuser also uses electricity as a power source, but it does not heat the oil, instead it breaks it down into very tiny droplets which are then expelled into the air, giving an extremely pure fine dispersal which can spread over a large area.
Nebulizing diffusers are often recommended by doctors for use by asthmatics and people suffering from COPD.
This is an example of a diffuser that uses an existing heat source to heat the oil for diffusion. In the UK, these are no longer very useful, as the old style lamp which used to give off so much excess heat has now been banned. Energy saving lamps are both the wrong shape and not warm enough to be useful for this purpose.
A note about scented candles and tarts (wickless candles)
Scented candles and tarts are not used for therapeutic purposes, because of the stearin and other ingredients mixed with the fragrance to make the candle.