PART 1 | In Conversation With Patrick Müller : The Science Behind Scent

To explore the technical foundations of perfumery, we spoke with Patrick Müller, who offers a thoughtful and precise perspective on how fragrance behaves, evolves, and ultimately connects with the wearer.

While perfume is often described in poetic terms, its structure is deeply rooted in chemistry. From the first impression to the lingering trail, every moment of a fragrance is shaped by the behavior of molecules and their interaction with both skin and environment.

In this first part of our conversation, Patrick reflects on the science that gives fragrance its movement, dimension, and life.

Fragrance is often described in layers. From a technical perspective, what causes each stage to appear over time?

The concept of top, heart, and base notes in perfumery is based on the volatility and molecular weight of the fragrance molecules used. Molecules belonging to the top are small and highly volatile, meaning that they evaporate quickly when applied. As they are light as a feather, these notes reach the nose first. However, they fade away typically after five to fifteen minutes and belong to the diffusion, also known as the sillage, of a perfume.

The middle notes belong to the core or body of a fragrance. They define the perfume’s character. These molecules are moderately volatile and have a medium molecular weight, emerging once the top notes dissipate, usually after around fifteen to sixty minutes.

Finally, the base notes build the foundation of a fragrance. I like to call them the “couch potatoes” of molecules as they are large and less volatile. These molecules can linger for hours, days, and even weeks, often blending with the heart notes to form the lasting impression of the fragrance.

All three stages belong to the so-called fragrance pyramid, a structure that helps us understand the character and evolution of a perfume.

Some materials can feel harsh in isolation yet become beautiful in a blend. What is happening here?

This phenomenon lies at the heart of both the art and science of perfumery. The brain interprets blended smells differently from how it interprets them individually.

An illustrative example often comes from rose. One might expect rose materials to smell purely floral, fresh, and soft. However, molecules such as rose oxide reveal metallic facets that can initially appear sharp or unfamiliar. Interestingly, rose oxide exists only in trace amounts in natural rose oil, yet it plays a crucial role in creating its diffusive floral green brightness.

There are also synergies between molecules that produce entirely new impressions. Indole, for example, can smell animalic on its own, yet in very small quantities within a white floral composition, it adds depth, richness, and a natural bloom.

Many strong or even unpleasant materials are used below their individual detection threshold. At these levels, they enhance, soften, or extend other notes without being perceived directly. It is similar to adding a pinch of salt to a sweet dish. The effect is subtle, yet transformative.

It is often said that fragrance smells different on everyone. Why is this so difficult to predict?

The way a fragrance develops on skin is influenced by a combination of biological, chemical, and environmental factors.

Skin chemistry plays an important role. The pH level, moisture and oil content, microbiome, and body temperature can all influence how a fragrance evolves. Environmental conditions such as heat and humidity can intensify a scent, while cold and dry air can mute it.

Even diet and skincare products can have an effect, as they interact with both the skin and the fragrance itself.

All of these elements create a complex interplay, making precise prediction nearly impossible. This is why it is always recommended to test a fragrance not only on blotters or fabric, but on skin.

Projection and sillage are often mentioned. How do they shape the experience of a fragrance?

Projection describes how far a scent radiates from the wearer, creating a kind of invisible aura. Sillage, on the other hand, is the lingering trail that remains in the air as someone moves.

Both are determined by the composition of the fragrance, particularly the volatility of its ingredients, as well as concentration and molecular structure. Skin chemistry and environmental conditions also play an important role in how these characteristics are perceived.

How do temperature and environment influence performance?

Temperature and humidity can significantly affect how a fragrance behaves.

High temperatures accelerate evaporation, causing a fragrance to open quickly but often reducing its longevity. Lower temperatures slow down evaporation, which can extend wear but reduce projection.

Humidity can enhance diffusion but may also make a fragrance feel heavier, while dry air can cause notes to evaporate more quickly and make smelling more difficult.

Even altitude can have an effect. At higher elevations, reduced air pressure and drier conditions can diminish the perception of scent, making fragrances appear softer or less intense.

Closing Reflection

What appears to be a simple, fleeting experience is in fact a dynamic interaction between molecules, skin, and environment. Fragrance is never static. It evolves continuously, shaped by both science and circumstance, revealing itself in layers over time.