Perfume is a blend of tens to hundreds of scent ingredients that are dissolved in alcohol and a solvent mixture. Its fragrance lingers after application. This trail of scent is referred to as the perfume’s sillage.
In a musical metaphor, perfume is often described as having three sets of notes that make up the harmonious scent accord. Each set unfolds over time, beginning with the initial impression of the top note, then the middle note and finally the base note. Perfumes are also grouped into families. The most well-known fragrance family is Floral, with five main subgroups including Soft Floral, Oriental, Woody, Amber and Chypre.
The majority of perfume’s odors come from natural aromatic plant extracts. These essential oils contain fragrant molecules that are produced by plants to protect themselves against herbivores or insects, to attract pollinators or to mark territory. These compounds can be extracted from the leaves, flowers, bark or root of a plant. However, many perfume ingredients are synthesized rather than derived from a natural source. This is especially common for coumarin and linalool, which are naturally occurring but often difficult to obtain in large quantities.
Other odorants are obtained from animal sources, such as castor oil pressed from the seeds of blackcurrant trees; musks obtained from beavers and deer; and ambergris extracted from sperm whales. In addition to adding a pleasant smell, these animal-derived products also have fixative properties that cause the perfume to stay on the skin for a longer period of time than would be possible without them.
A perfume’s sillage is also determined by the type and quantity of its components. For example, a heavier, richer perfume will have more base notes than a lighter, more airy one. In general, the higher the concentration of a perfume, the stronger its sillage will be.
Historically, the use of perfume was associated with social status and femininity. Queen Victoria, for example, was renowned for her extensive use of perfume. The perfumes she used, such as her favorite, Jontue, were a reflection of her refined taste and sense of style.
More recently, research has shown that women are more likely to choose a perfume depending on their mood and the occasion. A 2003 study by Herz found that women favored “dramatic” and “heavy” scents when going out for romantic encounters, while they chose “light” and “fresh” perfumes when going to the office.
Individuals may develop allergic contact dermatitis (red itchy skin) from exposure to perfume ingredients, even when the concentration is very low. In addition, certain fragrances can be irritants and can cause eye or nose irritation and asthma. These reactions can be triggered by a single or repeated exposure to a particular fragrance. Individual scents can also trigger a delayed hypersensitivity response that may appear several hours after exposure to the ingredient, and can affect areas that have not been directly exposed. In some cases, these allergic reactions are a manifestation of the psychological impact of a perfume.