"Eminenences Grises" By Luca Turin
Graham Greene once complained that, having struck it rich with his early novels, he moved to Cap Ferrat only to discover he was the poorest man on the peninsula. Science often works like that: you think you’ve cracked a problem and feel ready to turn on cruise control to coast for a while, when a strange fact comes up, sits at the back of the lecture hall and asks a question that reveals the depth of your ignorance. My day job is to design molecules for fragrances and flavors. I naively thought that if I could come up with something that smells good, is powerful, non-toxic and cheap to make, I would pretty much earn my keep. I was wrong. Time and again, the most experienced perfumers at fragrance firms ask for something completely different and far more mysterious. They want an “effect” material, not a smell.
Effect materials are as old as perfumery itself, and the first such were natural musks. By itself, natural musk has a strange, not particularly strong, not especially pleasant smell of unwashed underwear. But spray it on one wrist and overlay it with a well-known fragrance, and spray the fragrance alone on the other wrist for comparison. The absence of musks is akin to shutting one eye when looking into a 3-D viewer. The scene is the same, but the depth is gone. Other, equally legendary molecules have different effects. Salicylates turn the most banal floral composition into a real perfume, with majestic weight and sweep. Hedione has a magical ability to make things glisten, to fill the spaces between perfume components with a fresh, liquid air. Iso-E Super, long before Julian Schnabel got the idea on canvas, allowed perfumers to paint on black velvet.
But here’s where it gets strange. As it happens, some of these molecules are odorless to some people, including of course perfumers. This is particularly common with salicylates and musks. The perfumer Guy Robert once explained to me that he could not smell benzyl salicylate at all, but could instantly recognize its presence in a perfumery composition. He used a wonderful image: “I recognize it as if it were a friend seen from behind in a crowd, by the cut of his shoulders”. What is going on? Some blind people know that a light is there, even though they can’t see it. Do we have detectors other than those of smell to tell us a chemical is in the air ? What do these molecules have in common? This Rosetta Stone awaits a Champollion, who is probably in year 1 at ETH as I write.