The definition for sillage is very simple. Sillage means "the vapor trail." For perfume, it refers to how far away someone can smell the scent. Designing a perfume’s sillage is far from simple and understanding how to construct a perfume’s sillage is part of the challenge. Our expectations of sillage have changed as more perfumes use synthetics. Perhaps the most fascinating concept around sillage is how it mirrors women’s effort at being seen and heard in a male dominated culture.
Perfumes before the 1920s and 1930s were extremely expensive. For most women they were used only on special occasions. World markets changed during WWI and WII. Many already expensive ingredients were becoming prohibitively expensive to make profitable perfumes. At the same time, the number of synthetic replications of aroma molecules were increasing.
As synthetics came on the market, perfume companies would only accent their perfumes with them. The preference was to use naturals as much as possible. Just like wine, naturals will be different depending on where they are grown and the climate. Even a subtle difference in the naturals can have a tremendous impact on the final fragrance. What synthetics offered major perfume companies was stability and a substance easier to work with than the complexities of naturals. Synthetics are also substantially less money than naturals. All of these factors led to a shift away from naturals to synthetic aroma molecules being used in perfumes.
Initially synthetic aroma molecules were realized from the byproduct of manufacturing. Nitrobenzene was used to produce synthetic rubber, but its almond odor did not go unnoticed. Soon it found its way into more daily use products such as soap. In the late 50s and 60s, the advent of gas chromatography and mass spectrometry technology expanded chemists’ ability to analyze complex aroma molecules and replicate them. For example, musk’s which were becoming rarer, were one of the first groups of aroma molecules to be synthesized purposefully.
By the 70’s synthetics were the dominant ingredient in perfume and their presence was herald by the women’s liberation movement. Scent marking is a trait to establish dominance, and what we see (or rather smell here) is women’s perfume will had incredible sillage. The vapor trail and persistence of many of these perfumes of the 1970s and 80s was extraordinary and able to fill up a room leaving an aroma that would persist for hours.
Present day aroma molecule synthetics are evaluated on their sillage, impact, and persistence. But with the growing concern of how some synthetics adversely impact wellness, the formulation of perfumes has shifted, and many fine fragrances are considerably more subtle than those made from the 70-90s. The inclusion of naturals is more popular with fragrance houses again.
For those who prefer natural perfumes, sillage is a challenge, but it can be achieved by careful blending. Smaller molecules, like the ones found in citrus essential oils, will have a higher volatility and generally perfumes with an alcohol base will increase the “vapor” part of sillage but not the “trail” part. For a vapor to have its trail, it does need to persist. The persistence comes from the heavier molecules such as base notes. The additional challenge is that the heavier molecules sometimes cannot easily be perceived by the nose.
Carlos Benaïm the “nose” behind many famous fragrances including Calvin Klein, Ralph Lauren and Armani (to name a few) is not only a perfumer but also a chemical engineer. He describes that sillage exists in the interplay between the top volatile light notes and the heavier base notes. As a natural perfumer, I find his description a beautifully succinct way to describe the alchemy that happens when blends are constructed. His words also describes how many complex naturals work. For example, Champaca absolute, derived from the magnolia flower, is such a complex substance. It has many top green notes that play against the intermediate floral notes, and then several base notes that smell of honey and hay.
If you are interested in natural perfumes, then you must understand that there are limits to its sillage and duration compared to synthetics. That said, I have had some very interesting experiences with my creations. I often create my botanical perfumes in a solid oil base. For my personal use, I rarely use a dilution higher than 8%, which is quite low for a solid perfume (usually my solid perfumes are at a dilution of 20%). I wore a small amount on my chest when I was teaching yoga. My intention was that no one would smell it except me. But as I warmed up and the room warmed up, the blend's sillage was working its magic around the room. After the yoga class I got many compliments on my perfume, even from students in the back of the room! The effect was subtle but palpable, and a reminder that I should never discount the power of naturals botanicals.