"Perfume Time" By Luca Turin
A senior technician I once met in a fragrance firm decided to take an evening course in chemistry. When the exam came, he was asked to identify four unknowns using a roomful of instruments made available to him. Instead, he just smelled them and wrote down the (correct) structures. Smell miraculously enables us to see molecules, and the rules of perfumery are those of the invisible world. A molecule has an odor character (peach, salami, vanilla), a volatility (how long it takes to evaporate, from seconds for small molecules to days for big ones), and an intensity (roughly how little of it you can detect).
Spraying a perfume on warm skin is like firing a starting pistol on a beach crowded with different kinds of birds: the little ones start first, the herons and pelicans take a lot longer. Incidentally, if the beach were a smelling strip and a musk molecule was the size of a pelican, the smelling strip would be 200 kilometers across. Suppose now that you figure out an accord that requires an exact mix of birds of different sizes in flight towards your nose. That mix is going to happen only at a fixed time after the starting pistol, and may only last a few seconds. For example the smell of lychees absolutely requires, in a fruity mix, the presence of a hummingbird sized molecule called dimethyl sulfide. It lasts seconds on the skin, which is why lychee is a fleeting topnote. Conversely, you cannot have a musk topnote unless, as in Helmut Lang’s Velviona, you only put one ingredient in the mix. Perfumers know all these things empirically, but amazingly the only serious study of this was done in the mid-eighties at the great (and now extinct) firm of Roure. A young trainee was put in charge of measuring odor value (volatility vs intensity) for hundreds of pure molecules. The result of years of drudgery was a chart that you still see on office walls at Givaudan R&D (they bought Roure). It is supposed to be a secret, but photocopiers have put it in most perfumers’ hands.
Digest it (few have), and you have mastered Perfume Time. You can then make fragrances without scenery changes and intermissions, where every successive instant merges with the next one like chord modulations in late Richard Strauss. Prime examples: Calice Becker’s two Beyond Paradise fragrances. The name of the trainee who compiled the chart ? You guessed it.