One of the most important considerations in compounding perfumes or other cosmetic fragrances is that the odors of the compound materials must last as long as possible without losing their odor characteristics. Perfumers must keep this in mind whenever they make fragrances. There are said to be approximately four hundred thousand chemicals which possess odors, and each chemical has its own characteristic odor. Some have very low boiling points and vaporize within a few seconds; others retain their odors over several months. Also, some change odor when they are left in the air. For example, the oils of rose, jasmin and muguet each contain several hundred chemicals. The amounts of these chemicals are well balanced, and thus the essential oils give quite characteristic and harmonious odors. Once these essential oils are applied and left for several hours, however, the odor changes considerably.
We studied the odor tenacity of chemicals and essential oils, then, in order to facilitate fragrance compounding, since it is imperative that perfumes or cosmetics retain their pleasing odors as long as possible.
All chemicals and natural essential oils were obtained commercially. Each material was placed on a piece of bibulous paper (1 mm x 5 mm x 15 cm) withing a 5 mm% area. The surface area of the material was maintained constant in all the experiments. After a chemical or essential oil was placed on a piece of paper, this paper was placed in a room in which the temperature and humidity were maintained at 22°C and 45%, respectively. Three trained perfumers smelled the papers after 3 hours, 1 day, 3 days, 1 week, 1 month, and 3 months. When all three perfumers agreed that an odor had dissipated, the time by which this took place was recorded.