How Perfumers Work

The sense of smell, or olfaction, varies dramatically from one person to the next [source: Monell Chemical Senses Center]. What we can and cannot smell is often genetic, scientists are finding [source: Howgego]. Some people are simply born with the ability to smell more substances, and with greater sensitivity, than others.

Perfumers are some of those people. A "good nose" is critical to the work, as is curiosity [source: Academic Invest]. Great perfumers are constantly experimenting, combining essential oils in surprising ways as they search for some elusive aroma, an olfactory experience that achieves the desired emotion or effect when someone applies it.

That's the art. The science is molecular chemistry, the critical platform on which this creative experimenting and innovating rests.

Scents are particles of matter, comprised of molecules. When those molecules attach to any of the scent receptors in the human nose, the brain interprets them as smells [source: Stone]. The chemical properties of scent molecules determine not only how they smell but also how they act and interact, evident in the behavior of a perfume's three scent components: top notes, middle notes and base notes [source: Perfume.org]:

Perfumers use their knowledge of these molecular properties to design a scent that "unfolds," or evolves over time. And when they set out to create a scent, they start at the bottom, with the base notes.

Creating a perfume is a process of trial and error that can take weeks, months or years. Perfumer Ruth Mastenbroek spent three years creating her self-named signature fragrance (2010). Christopher Brosius spent five years creating his award-winning Snow (2000), which smells like snow [source: Gray]. But they were creating for their own lines; when creating for a client, a month or so is more common [source: Bradley].

A perfumer typically begins with an olfactory goal in mind, and the process starts with selecting essential oils for the base notes [source: Perfumer's Apprentice]. Notes are individual scents. When various notes are combined, they form a new scent called an accord. A base accord, middle accord and top accord make up a perfume.

To create a base accord, a drop of each selected essential oil is applied to the end of a separate test strip (or "scent strip"), a long, thin piece of blotter paper with room on one end for notes. Holding those test strips together, the perfumer smells the resulting accord. If it works, voila. Base accord.

Far more likely, the experiments start.

Proportions of the essential oils may be adjusted incrementally, repeating the test-strip process for each new ratio, making comparisons and taking notes. A third or fourth essential oil may be added. One of the original essential oils may be removed. And with each new combination comes another round of test strips, ratios, comparisons and notes [source: Perfumer's Apprentice].

When the perfumer is holding an array of scent strips that emits the perfect base accord, the process starts anew for the middle notes, eventually resulting in the middle accord. Once the middle accord is perfected, that set of strips is paired with the strips of the base accord, and experimenting begins again, this time making adjustments based on the interaction between the base and middle accords. And then again with top notes – creating the top accord, joining that accord with the middle and base accords, and experimenting until the combination of the three, which will be the perfume, is just right [source: Perfumer's Apprentice].

Achieving this result can take hundreds of trials [source: Academic Invest]. But for those with the dedication to break into the world of commercial perfumery – there are apparently more working astronauts than working perfumers -- it's a labor of love [source: BBC].

Industry statistics have just 500 people working as noses in the perfume industry, so it takes more than a good sniffer to make it as a perfumer [sources: Williams, Perfumers World].

Some artistic souls with amazing noses stumble into the career, but that's rare. Many start their careers working in perfume stores or as lab technicians for perfume manufacturers [sources: Bradley, College for TN]. Others are chemists who discover a love of scent and follow their noses [sources: Bradley, Givaudan].

A degree in chemistry is required, as are years of additional, specialized training in cosmetic science and the specifics of perfumery [source: Academic Invest]. Lots of colleges, universities and private organizations offer perfumery courses, and some offer certificates in the art, but specialized degrees are harder to come by and often require studying at a dedicated perfume school. Those are relatively few, and the most prestigious ones are highly selective: The Givaudan Perfumery School in Paris accepts about 2 percent of its applicants [source: Hume]. For comparison, Harvard University accepts about 6 percent [source: U.S. News & World Report].

Perfume schools offer courses in topics like scent formulation, applications of natural vs. synthetic essential oils, olfactory evaluation and physical-chemical analysis. Trainees learn the scents and qualities of hundreds of natural and synthetic chemicals, developing their olfactory memories [sources: College for TN, ISIPCA]. They spend years as apprentices to master perfumers [source: College for TN].

Students typically also study marketing and business subjects, because perfumery isn't all test strips [source: ISIPCA]. It requires an understanding of consumers, the retail industry, quality control and business management: what people want in a perfume, how to analyze industry trends, how to tell the techs who prepared test batch 3 they messed up the formula [source: Academic Invest].

A formula that took 491 trials to perfect. But that's par for the course. Perfumers are a patient folk.

Right now, in a lab somewhere, someone is adjusting the ratio of musk to vanilla to orange for the 61st time, remembering a decades-old citrus grove, wondering what an oakmoss note might do for the accord ...