Fragrance is a mixture of chemicals that emits a pleasant smell. It can be derived from natural raw materials such as herbs and flowers or synthetic aroma compounds. It is used in a variety of cosmetic products including perfume and cologne, but also in other personal care items such as soaps and shampoos. It can also be found in cleaning products such as fabric softeners and dryer sheets, room fresheners, deodorants and even some laundry detergents. Some fragrance ingredients have been linked to a range of health concerns including cancer, allergies and asthma.
Fragrances are generally grouped into categories based on the scent they produce. The three main categories are top notes, middle notes and base notes. The top notes are the odors that evaporate first and provide the initial impression. They usually last 5-30 minutes after application and can include citrus (lemon and orange), light fruits such as berries or citrus fruit, and herbs like lavender and sage.
The middle notes provide the body of the perfume and can last 2-4 hours. Middle notes are typically comprised of more complex aroma molecules than top notes, and are a combination of floral and spicy scents. The base note is the heaviest of the three notes, and lasts for several hours after the heart note has faded. The base note is usually composed of large molecules that give a rounded, smooth, and balancing scent.
Natural scents will vary from one supplier to the next, based on factors such as when and where the raw material was grown or harvested, and the extraction method employed. This can result in a slight difference in the scent of two perfumes that have the same name, such as Chanel No. 5. This variation can be further compounded by dilution.
Perfumes are usually composed of various raw materials, which are then diluted with a solvent. The most common solvents are ethanol and isopropyl alcohol. Ethanol is less polar than many other fragrance materials, making it easy to dissolve them. Isopropyl alcohol is also widely used in perfumery and is a very effective solvent, but it can leave an unpleasant residue on skin and equipment.
While it is possible to make perfume from a variety of materials, the majority of perfumes are made from synthetic aroma compounds. They are produced by combining multiple chemical processes such as hydrocarbon chemistry, aromatic ring synthesis and carbonylation. The resulting compounds are then formulated into a perfume by adding diluents, preservatives and colorants.
Perfumes and colognes have been popular since ancient times, with the practice reaching its height in Europe during the 1500s, when Louis XIV was known as the “perfumed king.” Fragrance is now added to a wide variety of personal care and cleaning products. Some of these products are intended to promote hygiene, such as perfumed soaps and hand lotions; others have a more psychological effect on the wearer, such as scented hair sprays and body powders. A wide variety of health risks have been associated with the use of some fragrance chemicals, and the International Fragrance Association (IFRA) has developed a system for testing fragrances for safety.