Perfumes have three notes, the first of which is smelled when applied.
There are several fragrance categories: perfume is at the top, followed by eau de parfum, eau de toilette, and eau de cologne, each containing a lesser degree of aromatic oils, respectively. The lower the concentration of aromatic compounds, the shorter the shelf life of the perfume. The scent is highly prized precisely because it lasts from morning to night and has good wear, meaning the scent stays fresh as the day progresses. In fact, a good one is designed to smell great throughout its various stages of use.
A bottle of perfume.
Aromatic compounds used in fragrances have complex chemical interactions. While consumers might imagine a group of corporate executives sniffing bottles of various concoctions to see what smells best, the truth is far more complicated. Fragrant compounds tend to decompose quickly when exposed to heat, light and air, so in order for a scent to last throughout the day, dozens or even hundreds of ingredients are used to keep the product “blooming”. Essentially, as one group of compounds is spent, another revives the scent and adds its own tone. The perfume is said to have three notes that work together to form the lasting fragrance.
Tonka beans, which are sometimes used in perfumes and toilet water.
The top note is the initial scent when applied. This smell only lasts for a few minutes to an hour and can be a little strong. As it fades, it reveals the fragrance’s middle note, also called the fragrance’s heart or body. The aromatic compounds that make up the heart last longer, but eventually give way to the base note, or underlying tone. The ideal base note scent takes time to develop, so initially it is not as pleasant but is masked by the middle and top notes. By the time they soften, the base note is fully developed and ideally helps to reinforce the other notes. That’s the scent left over at the end of the day.
Citrus fruits are often used in perfumes.
Understanding this symphony of interactions makes it easier to see why a perfume might smell great when first applied, but can take on a rancid or heady note later in the day. In this case, the base note of the fragrance is not to the user’s liking. On the other hand, a fragrance can smell better as the day goes on, if the wearer’s olfactory senses prefer the base note to the top and middle notes. When a person finds a fragrance that really pleases them from morning to night, they have discovered love for all three notes that make up the perfume.
Perfumes often include essential oils.
With all that people associate with these products, it might seem counterintuitive that scented chemicals are often caustic irritants in concentrated form. Therefore, fragrances are made with diluted and compounded essential oils. Generally, the concentration is around 20-40% for perfume, 10% less for parfum, 20% less for eau de toilette, and cologne contains only 2-5% aromatic oils.
While flowers constitute the largest source of chemical compounds used in commercial fragrances, bark, woods, resins, leaves, tobacco and citrus also contribute to the different aroma categories. Synthetic chemicals have also become popular and are more reliable from an industry perspective as they are consistent to work with, unlike natural products. The use of synthetic compounds is a new arena with an untested history in terms of health and the environment. Synthetic musk, for example, was found in the Great Lakes due to nearby chemical processing. It was also found in human fat cells and breast milk.
Buyers who prefer to buy perfume made from natural compounds should look for the words “all natural ingredients”. These products are likely to be more expensive and harder to find. Ingredients listed as “imitations” or “natural synthetic compounds” refer to synthetic chemicals created to copy real-world chemicals. The synthetic version may have a much stronger odor than its more expensive natural versions, but the compounds it is made of are different elements from naturally occurring compounds and are not “natural”.
While synthetic chemicals are increasingly used in traditional fragrance categories, they have also given rise to a new category of fragrances, grouped under the heading Ozone or Oceanic. This joins the existing categories of Floral, Fruit, Green, Wood, Amber and Leather and Oriental.