Ep 25: Why Are Perfumes So Complex? The Science Behind your Favorite Fragrances

Perfume is one of those things everyone uses but almost no one thinks about. It might seem like you're just spraying a fragrance onto your body and voila you smell good, but it's actually way more complex than that.

A finished fragrance is made up of three things working together: aromatic compounds (the actual scent molecules, either extracted from plants or synthesized in a lab), fixatives (ingredients that slow down evaporation and help the scent last), and a solvent to hold it all together. Solvents are just ingredients that dissolve things. In perfume, that solvent is almost always ethanol; the standard ratio is about 98% ethanol to 2% water.

The concentration of those aromatic compounds is what separates a parfum from an eau de toilette. More concentrated = stronger and longer-lasting, and also usually more expensive. Here's how the classifications break down:

1. Parfum: 15-30% aromatic compounds

2. Eau de Parfum: 8-15%

3. Eau de Toilette: 4-8%

4. Eau de Cologne: 2-5%

(Eau de cologne, for what it's worth, was originally invented by Italian perfumers working in Cologne, Germany in the 1700s; it was made from rosemary and citrus dissolved in wine. It has since become a generic term for any weakly concentrated fragrance, and somehow also "men's fragrance" as a category. Fun little detour.)

The other thing worth knowing is how a fragrance changes on your skin over time. Perfumes are built in layers called notes, and different molecules evaporate at different rates. Top notes hit first; they're small, volatile molecules that make the immediate impression but fade within the first few minutes. Heart notes (or middle notes) emerge as the top notes dissipate, usually within the first hour. Base notes are the last to show up and the longest to stick around; sometimes 24 hours or more. A fragrance you test on a strip at Sephora is not the same fragrance you'll smell on your skin three hours later. This makes purchasing perfume kind of annoying, but it's also really fun that perfume is a journey, rather than a destination.

Products mentioned in this episode:

Versace - Crystal Noir

Carolina Herrera - Good Girl Supreme

Yves Saint Laurent - Libre Intense

Kayali - Vanilla 28

Versace - Yellow Diamond

Dolce & Gabbana - Light Blue

Maison Francis Kurkdjian - Baccarat Rouge 540