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. The alcohol is removed under vacuum also. The alcohol is recovered and used in colognes and lotions.