If you’re into the perfume hobby a little bit beyond the surface level, you might have heard the word “fixative” mentioned here and there.
It’s one word in a sea of often (sometimes deliberately) mystifying terminology related to perfume, along with terms like projection, sillage, and perfume concentration. But what exactly is a fixative? What role does it play in a perfume?
Fixatives are a class of perfumery ingredients whose purpose is to “stabilize” a perfume, as well as provide greater lasting power on skin. They usually make up the “base notes” of a perfume, and are “heavier” materials like woods, musks, resins, leather, and molecules like ambroxan and ISO E Super.
Want to know more? Let’s take a deeper dive into the amazing world of perfume fixatives.
What Is a Fixative?
As I mentioned before, fixatives are perfume ingredients whose purpose it is to “stabilize” a formulation as well as increase its longevity and durability. But why does perfume need to be stabilized? In what way does perfume become unstable?
It all comes down to a little something called “volatility”.
What Is Volatility?
“Volatility” is a word you might remember from your high school chemistry class (if you could stay awake through it). It refers to the rate or tendency at which a given material evaporates, or “vaporizes”.
An example of a high volatility substance would be alcohol. If you’ve ever cooked with alcohol, you’ve seen this in action.
Imagine: you’re cooking up a batch of sauteed mushrooms and decide that you want to add a splash of white wine in order to deglaze the pan.
When you first put the wine into the pan, you get a rush of winey-ness straight to the nostrils; after that, though, the aroma of the wine is a lot less evident. That’s because the alcohol has evaporated! In fact, alcohol is one of the most volatile common substances. It also happens to be one of the critical ingredients of perfume.
On the other hand, one example of a substance with low volatility would be your average workaday cooking oil. Even when exposed to high heat, cooking oil remains condensed, and doesn’t undergo a state change like alcohol.
How Does Volatility Relate to Perfumes?
It relates to perfumery in a huge way! After all, perfume is the synthesis of chemistry and art.
Any perfume is made up of a combination of perfume oil and alcohol (or oil, but let’s just set that to the side for the moment). Every material contained within a perfume oil has its own volatilities. Some materials, such as citrus fruits, are very volatile, tending to evaporate almost as quickly as alcohol.
Other ingredients, such as sandalwood, musk, myrrh, or benzoin, have comparatively lower volatilities, meaning that they evaporate relatively slowly.
If you make a perfume made up solely of highly volatile ingredients like citrus and herbs, then it’s not likely to last very long. A lot of the scent would evaporate along with the alcohol, and you wouldn’t have much of anything left on your skin.
Some fragrances, such as traditional eaux de Cologne, are made expressly with this purpose in mind; just a simple, after shower refreshment.
You need both high volatility and low volatility ingredients to craft a great perfume. But which class of ingredient do fixatives fall into?
A: High volatility ingredients, or B: low volatility ingredients?
The Role of Fixatives in Perfume
If you guessed B: low volatility ingredients, then you were right on the money!
Fixatives are ingredients that have low volatility. Their purpose is to stabilize a composition almost by “weighing” it down.
Think of it this way.
Imagine you have a bundle of juicy, aromatic oranges and fresh rosemary, but no table to put it on. Throw in some fixatives, and voila! Now you’ve got a nice wooden table to plop your oranges down on.
Fixatives are the base of a fragrance, giving it solidity and form, helping to “equalize” the vapor pressures of other ingredients in the formulation. In doing so, they make highly volatile ingredients less volatile and longer lasting on skin.
What Are Some Common Fixatives?
Most of the time, fixatives are “heavy” notes like wood, leather, amber, musk, vanilla, oakmoss, and resins such as myrrh, benzoin, frankincense, elemi, and tolu balsam. Such ingredients tend to make up what are known as the “base notes” of a fragrance, the bottom of the perfume pyramid which will linger the longest on skin.
However, fixatives can also be aroma chemicals such as ambroxan (a critical ingredient in popular fragrances like Dior Sauvage), javanol (a synthetic sandalwood aroma chemical), cashmeran (a “cashmere wood” aroma chemical), ISO E Super (a synthetic cedarwood aroma chemical) or a whole host of synthetic musks.
But fixatives don’t necessarily even have to have a smell. Sometimes, fixatives can be entirely odorless molecules, such as diethyl phthalate or triethyl citrate, simply employed in a fragrance because of their low vapor pressures.
The Final Word
In short, fixatives are one of the most important ingredients in perfumery, serving in many cases as the “bones” upon which the rest of a perfume can be built. Without fixatives, almost every perfume would be an eau de Cologne, something you just slap on and have to reapply twenty minutes later. They are the critical components which determine a fragrance’s lasting power on skin.
So, what is a fixative?
Fixatives are perfume ingredients which stabilize the volatilities of other ingredients in a perfume as well as increase lasting power. They are usually stronger, heavier materials like woods, resins, musks, vanilla, or certain aroma chemicals like ambroxan or javanol.