All fragrances go through an evaporation process and lose strength over time. What most people don’t know, however, is that the character of the fragrance will change as it evaporates. That’s because the various essential oils and aromatics, or “notes”, that make up the fragrance evaporate at different rates:
Top notes are the most volatile oils. They provide a strong initial impact and evaporate quickly. Citrus oils tend to be top notes. Some fruits are also top notes.
Middle notes are less volatile. They are not as strong at first, but they take longer to evaporate. Middle notes remain detectable in the air — longer than top notes. Florals tend to be middle notes, as well as some fruits and spices.
Base notes are the least volatile and longest lasting. They are subtle, yet steady aromas that linger through the end of the fragrance life. Base note oils are mostly woods and some spices.
Making a fragrance “stronger” doesn’t mean it will last longer, because that usually means including more top notes. The goal is to include a variety of notes, so that as the top notes fade away, the middle notes and base notes take over, extending the life of the fragrance. This also adds depth and richness to the fragrance, further enhancing your image of quality.