Sillage

Sillage is not an ingredient. It is a property of a composed fragrance experienced in space and time. A fragrance with strong sillage is one that leaves a detectable trail; a fragrance with close sillage stays near the skin.

Sillage is a spatial and temporal phenomenon. When a person wearing perfume moves through a room, they create turbulence in the air behind them. This turbulence carries fragrance molecules from the skin and clothing into the environment, forming a trail that persists after the person has left. The trail's intensity, duration, and reach are what perfumers and wearers call sillage.

The word entered English perfumery vocabulary directly from French, where it has been used since at least the seventeenth century in nautical contexts. The analogy is precise: a ship's wake is visible and measurable long after the hull has passed, but it eventually dissipates. Sillage behaves identically.

Three factors determine sillage. First, the volatility profile of the composition: materials with high vapour pressure (top notes, certain synthetic musks, ambroxan-type diffusers) project more aggressively into the surrounding air. Second, the concentration and amount applied: more molecules on the skin means more available for diffusion. Third, the physical movement of the wearer: walking generates more turbulence than sitting, so the same fragrance produces stronger sillage in motion.

Sillage is often confused with projection and longevity. Projection is the radius of scent around the body while stationary — it answers 'how far can someone smell me right now?' Longevity is the total duration the scent remains detectable on skin. Sillage answers a different question: 'what do people smell after I've already left?'

A fragrance can have strong projection but weak sillage (if its diffusive materials are highly volatile and don't persist in air). It can also have weak projection but noticeable sillage (if its base notes are substantive enough to cling to fabric and release slowly as the wearer moves).