Fragrance diffusers allow a fragrant liquid to slowly evaporate. This process gradually fills a room with whatever scent is contained in the liquid. The fluid in a diffuser usually consists of essential oils in an inert base, often water. This liquid is usually contained in a small but attractive glass or ceramic vessel, and a bundle of reeds is placed into this fluid. The reeds distribute the scent gently throughout the room.
The process of wicking is essential for the operation of fragrance diffusers. Wicking draws liquid slowly upward against the force of gravity. It is made possible by the interplay of forces working at a molecular level. Plants naturally use this process to draw water into their leaves and branches.
Many plant materials retain the cellular structure needed for wicking even after they are no longer alive and growing. Most wood is able to wick water along the grain. Reeds, which are fibrous and woody, have this property as well and are much easier to work with than actual wood. Diffusers make use of this property by employing reeds to slowly absorb liquid and wick it upwards where it can evaporate gradually though the pores in the reed.
Home fragrance diffusers are available in a wide variety of styles. The simplest consist of plain and unobtrusive glass vessels with narrow necks to minimize unwanted evaporation from or contamination of the scent reservoir. Other versions are more ornate and may be made of elegant colored glass or elaborately decorated. Those interested in crafts can also create their own fragrance diffusers from any suitable and interesting glass or ceramic vessel.
It is easy to control the amount of scent released by a fragrance diffuser. If more reeds are used or if the reeds are more deeply submerged in the liquid, then more liquid will be diffused and a stronger scent will be produced. If a more subtle scent is desired then the number of reeds can be reduced or the level of the fragrant liquid lowered.
A key advantage of fragrance diffusers is the very gentle nature of the diffusion process. Other methods for distributing fragrances, such as heated diffusers or scented candles, operate at high temperatures. Essential oils are often quite delicate, and their chemical structure can be damaged by exposure to heat, making the fragrance either weaker or less pleasant. Fragrance diffusers, in contrast, are much gentler in their handling of essential oils and are better able to preserve and distribute their scent.