How Perfume Is Made, Labeled and Worn

A perfume is a blend of aromatic materials dissolved in alcohol, usually a specially denatured ethanol with a little water. Everything else on the bottle, from the strength printed on the label to the way it changes over an afternoon, follows from that simple recipe: how much aromatic material is in the alcohol, which materials they are, and how fast each one evaporates from your skin.

How it is made

A perfumer works from a palette that can run to well over a thousand materials, and most modern perfumes mix two broad kinds.

Natural materials come from plants and, far less often today, animals. The extraction method depends on the plant. Lavender, rose and many herbs are steam distilled to give essential oils. Delicate flowers such as jasmine and tuberose do not survive steam well, so they are usually extracted with solvents, producing a waxy concrete and then a concentrated absolute. Citrus oils such as bergamot and lemon are pressed from the peel. They are costly and vary from harvest to harvest.

Synthetic materials are made in a lab, either copies of molecules found in nature (vanillin, the main aroma of vanilla, is the classic example) or molecules that do not exist in nature at all. Synthetics made modern perfumery possible: the aldehydes in Chanel No. 5, released in 1921, are often cited as the turning point. They also replaced animal materials. The musk once taken from musk deer now comes from synthetic musks, and ambergris, a rare substance from sperm whales, is largely replaced by lab-made molecules such as Ambroxan.

Neither group is automatically safer. Natural oils contain compounds such as linalool, limonene and geraniol that can trigger skin allergy in some people, especially once they oxidize. That is where the International Fragrance Association (IFRA) comes in. It is the industry's own body, and its IFRA Standards, based on safety assessments by the Research Institute for Fragrance Materials, ban some materials and cap others by product type. Oakmoss extracts are limited because of two allergenic compounds they contain, and a synthetic lily-of-the-valley note known as Lyral has been prohibited. Bergamot oil is usually treated to remove furocoumarins, chemicals that can cause blistering rashes when the skin is then exposed to sunlight. The standards are updated in numbered amendments, which is why a reissued classic can smell a little different from the version you remember.

The finished concentrate is mixed into alcohol, rested for weeks, then chilled, filtered and bottled.

How it is labeled

The name on the box after the brand, such as "eau de parfum", tells you roughly how much aromatic concentrate is in the alcohol. These terms are industry convention rather than legal definitions, so one brand's eau de toilette can be stronger than another's eau de parfum. Typical ranges look like this:

• Parfum or extrait de parfum: around 20 to 30 percent concentrate, sometimes more. The strongest and usually the most expensive, often sold in small bottles.
• Eau de parfum (EDP): roughly 15 to 20 percent. The most common strength for current releases.
• Eau de toilette (EDT): roughly 5 to 15 percent. Lighter, often brighter on top.
• Eau de cologne (EDC): roughly 2 to 5 percent. Light and quick to fade, traditionally citrus-led.

Higher concentration usually means a scent lasts longer and stays closer to the skin, but the materials matter as much as the percentage. A citrus-heavy parfum can fade faster than a woody eau de toilette.

Descriptions in stores and online usually break a perfume into top, heart and base notes. Top notes are the small, light molecules you smell first (citrus, fresh herbs, some fruits), and they tend to fade within the first quarter hour or so. Heart notes, often florals and spices, carry the middle hours. Base notes such as woods, resins, vanilla and musks are the heaviest and can linger for many hours, sometimes into the next day on clothing. The pyramid is a simplification, since most materials evaporate gradually and overlap, but it explains why a perfume can smell sharply different at the counter and an hour later.

How to wear it

The same perfume smells different on different people, and the reasons are mostly practical. Dry skin holds scent less well than moisturized skin, so applying an unscented moisturizer first can help a fragrance last. Body temperature, sweat and what is already on your skin all change how quickly notes evaporate.

Rubbing your wrists together after spraying is often said to "crush" the notes. Molecules cannot really be crushed that way. The more plausible explanation is that friction warms the skin and can speed the evaporation of the lightest top notes, though there is little hard testing behind it. Pressing your wrists lightly together, or simply letting the spray dry, does no harm either way.

Spraying on clothing makes a scent last longer, because fabric does not warm or absorb it the way skin does, but oils and dyes in perfume can mark silk and pale fabrics. Test on an inside seam first, and keep it off pearls and other porous jewelry. Do not spray near the eyes, and if a perfume leaves a rash that persists, stop using it and see a dermatologist.

Most people stop noticing their own perfume within minutes, a normal adaptation called olfactory fatigue, which is why it is easy to overapply. Two or three sprays are plenty for most eau de parfum.

Storage decides how long the bottle stays as it was made. Heat, light and air break down aromatic materials, and top notes go first. Keep bottles closed, in their box or a drawer, somewhere cool, and not on a sunny windowsill or in a bathroom that steams up every morning.