Let’s start with the basics: When it’s listed that a perfume has a 12% concentration, it means that there is in the bottle 12% of perfume concentrate and 88% of a mixture of alcohol and distilled water.
Perfume concentrate, which refers to the pure oil, is the mix of all the fragrant raw materials melded together according to the perfumer formula. The perfumer formula contains usually between 30 to 60 different raw materials, natural or synthetic. Some fragrances could be formulated with as little as 10 or fewer concentration materials, while others have more than 150. Generally, 30 to 60 concentration materials is the average for a perfume. Melding together all of the raw materials creates an especially oily, loud mixture which could be unpleasant to apply directly on the skin.
You may be under the assumption that if this oily concoction were applied directly on the skin it would be incredibly powerful. However, alcohol helps raw materials to evaporate and is key to produce this “splash feeling” as the fragrance is applied. Even though applying the oil mixture alone would certainly stay longer on the skin, it won’t have the same sillage, the same aura.
Generally, the higher a concentration is, the stronger the perfume should be. Even so, it’s not quite this simple as some raw materials are more powerful than others. Depending on its contents, sometimes a 15% fragrance could be stronger than another one concentrated at 20%.
Traditionally, the designations for fragrances were very standardized, and correlated with an increasing concentration: Eau de Cologne, Eau de Toilette, Eau de Parfum, Parfum. This is a vast subject that we’ll delve into in another post.
In the real world these codes have long since been shattered, and these labels are more the result of a marketing positioning than the reflection of a bottled reality.