There is a lot of folklore associated with perfumery. Many of the recipes for the best perfumes are guarded trade secrets. In the last few years, all major perfumers have a staff of organic chemists and perfume compounding is no longer an art, but a science. Other materials known as fixatives retard and modify the evaporation of volatile essential oils. Odorants are what give the perfumes the characteristic odor.
Many factors determine which method is used.
Among these are cost, quality of essence, and use of the product. Concretes are the purest of the natural odorants. They are obtained by using a hydrocarbon solvent to dissolve the essential oils out of the plant. The liquid is then removed under vacuum by mild heating. Absolutes are extracted from the non-volatile materials with alcohol.