Longevity, projection and sillage

Longevity is the length of time for which a fragrance remains detectable on the chosen surface. In this article, we also call this perfume’s lasting power. The scientific review treats longevity and fragrance diffusion as distinct properties; when assessing a result, it is important to state what was observed and under what conditions.

For a practical note, we suggest answering two questions: is the fragrance still detectable, and what impression does it make now? For example, the notes “detectable up close” and “the citrus accent I initially liked is no longer present” may describe the same test. This is an illustration, not the result of a study of a specific perfume.

Do not compare figures if one was obtained on paper and the other on skin. The engineering review examines the importance of the medium, evaporation and interaction with skin. It does not provide a single duration for all bottles or all people.

The product-measurement status for this article is “unmeasured”. This means that we do not provide verified numbers of hours for a specific fragrance here. The label is neither a poor nor a good longevity rating.

Explore this topic in the guide: Which perfumes last longest?.

Perfume projection describes how a fragrance can be detected at a distance from its source. Fragrances of the World describes diffusion similarly: a fragrance’s ability to diffuse from the skin and be perceptible around it. In this article, the word “projection” helps distinguish a spatial impression from duration.

For a precise discussion, saying “strong perfume” is not enough. Ask instead whether it can be detected only up close or at a normal conversational distance. These are suggested descriptive terms, not a universal rating scale. Record the other person’s answer together with the environment and the time since application.

Scientific models link fragrance diffusion to evaporation and airborne transport. They do not provide a basis for assigning the same projection-decay curve to every product. We therefore do not state that every fragrance is most detectable only during the first few minutes.

When choosing a fragrance for work, also discuss how noticeable you want it to be. The request “I want a long-lasting fragrance that is detectable only up close” describes the need more precisely than simply “I want something strong”. You must still check the answer with the specific product, rather than relying on a general category name.

Sillage is the scent trail left as the person wearing a fragrance moves. This definition is given in the perfume-engineering review. Projection helps describe detectability around the source, while sillage emphasises movement and the trail left behind. The terms are related but useful for different questions.

The review examines a moving fragrance source and diffusion models. A laboratory model is not a promise of how many metres the sillage of your chosen fragrance will extend. We do not turn its result into a shop rating or a single distance that applies to everyone.

When speaking with another person, we suggest asking simply: can the fragrance be detected as I pass, and does it linger after I have gone? Agree in advance that this will be a brief observation, and do not carry out such a test with someone who finds the fragrance unpleasant.

Detecting the fragrance on returning to a room is not, by itself, a precise measurement of sillage. Other fragrance sources may also be present. Keep this everyday impression in your own notes rather than presenting it as a laboratory result for the product.

Fragrance evaporation and diffusion depend on more than the name of a substance or its molecular mass. The engineering review discusses vapour pressure, interactions between mixture components, the carrier and interaction with skin. Here, vapour pressure helps describe a substance’s tendency to enter the gas phase.

The rule “a light molecule evaporates first; a heavy one remains” is therefore insufficient to explain every composition. Nor can penetration data for different molecules be presented as a measured difference between two people. These are different comparisons.

IFRA explains that the concentration designations eau de toilette and eau de parfum have no strict international definition; they are used according to industry practice. A designation can provide orientation, but it does not itself prove the longevity or projection of a specific product.

If you compare two variants, record their full names and concentration designations. Do not judge only from similar packaging or names. This article is intended to help you ask a more precise question, not to calculate a number of hours from a designation.

Explore this topic in the guide: Extrait de parfum: What Does the Label Mean?.

Olfactory adaptation means a decrease in sensitivity to an odour after repeated exposure. The Foods study discusses this phenomenon while assessing the effect of personal fragrance on sensory-evaluation tasks. Sensory evaluation is the assessment of samples using the senses.

In the study, which used a specific fragrance and a laboratory procedure, participants’ odour-threshold and discrimination scores decreased under fragranced conditions. This is not a study establishing when every person stops smelling their own perfume. Nor does it establish a considerate number of sprays for people nearby.

A single “I can no longer smell it” cannot establish whether the cause is adaptation, a reduction in the fragrance, or another circumstance. Before applying more, we therefore suggest pausing and, if appropriate in the situation, asking another person for a voluntary observation.

Do not use this explanation for self-diagnosis. If a change in your sense of smell concerns you, consult a doctor. This text helps discuss the perception of perfume and does not replace an individual health assessment.

Begin with a clear question: do you want to compare duration, detectability at a distance, or the trail left while moving? Choose one fragrance for a single test and record where you dabbed or sprayed it. This is an editorially suggested method for personal notes, not a validated measurement method.

Record the start time and choose later assessment times that are convenient for you. Describe your perception according to the same principle each time. There is no need to smell your skin deliberately at very short intervals or look for a number that matches an online description. Keep “I don’t know” as a valid result too.

If another person agrees to help, ask about detectability at a normal conversational distance and as you pass. Do not begin with “is it very strong?”—that question suggests an answer. Instead, ask the person to describe in their own words what they notice.

Next time, repeat your chosen test in an environment that is usual for you, following the product’s directions for use. A personal note can help you decide, but it does not become a result for all buyers. If the fragrance causes discomfort, stop the test; there is no need to prove its longevity by spraying more.