The Science of Smelling Great

    Being 25% Italian, I am always excited to come vist Italy. I first came my freshman year of high school with my mother and 2 family friends, and we stayed in Rome the whole time. By the next time I came, two years had passed, and I visited via a program being run by my high school; we took a fast paced tour of the whole nation, visiting many major cities such as Florence, Rome, and Sorrento, before crossing the Adriatic Sea and visiting Greece. This, however, is my first time visiting Siena, and, so far, I must say that I am rather pleased with it.

    One thing I have looked forward to doing every trip is buying Italian goods not usually found in the U.S. The first time I came, I had my heart set on purchasing a fine Italian blazer, and an equally fine tie to go with it. The second time, I was excited to purchase goods from Greece (and their terrible economy driving down prices certainly didn’t deter my wishes...). This trip, however, especially after reading in Tom Mueller’s Extra Virginity about how one of the original uses for olive oils was to hold different scents for colognes and perfumes, I decided that my big purchase for this trip would be a new Italian cologne or two, even though I knew that mine would have to be of the less long-lasting alcohol based type.

    During one of our free hours in Rome, a few friends and I entered a small mall in order to take a break and cool down from the scorching Roman sun. After drinking an espresso made with Illy espresso beans, my favorite kind, we decided to split up and explore the mall for about 20 minutes. After a bit of walking around, I found exactly what I was looking for: a cologne store. After exposing my nostrils to dozens of scents I came upon one called “Mistero di Roma Uomo.” It instantly passed the “does the bottle look cool?” test, and, a few moments later, it passed the arguably more important smell test. I knew that buying such a fine cologne could put my life in danger, as I would have to swat away hundreds, if not thousands of Italian women, but I decided to take the risk for the sake of smelling great, and left the store satisfied.

Above is an accurate representation of what  look like while wearing Mistero di Roma Uomo.

Buying such a fine scent, however, got me thinking about what exactly colognes were, and how they worked. Recently, I learned that colognes are composed of two main ingredients, the essential oils and the denatured ethanol solvent. The essential oils are what give the cologne its distinct scent, and alcohol is used merely to dissolve the oils. Since ethanol is a volatile substance,  it will release the smell of the cologne continually as your body heats it, allowing users to smell great all day long. The concentration of the essential oils determines the official type of the cologne, with aftershave having very low concentrations, eau de cologne being 2-5% essential oils, eau de toilette being about 10%, and eau de parfum being 15% (http://www.askmen.com/fine_living/keywords/cologne.html). In order to keep the scents of the oils pure, the ethanol is denatured, meaning that it contains additives that remove the alcohol smell of the ethanol. One denatured alcohol I found also contained isopropyl myristate, which helps absorption of the essential oils into the user’s skin, and monopropylene glycol, which is a cosolvent that helps control the evaporation of the cologne, ensuring that it does not evaporate too quickly (http://mistralni.co.uk/catalogue/product/85/Perfumers-Alcohol). After looking at the structure of monopropylene glycol (shown below), it’s easy to see why it’s boiling point is about 110 degrees celsius higher than that of ethanol (78 vs. 188 degrees); it has a huge hydrocarbon chain that would allow for more london dispersion forces to be present and hold the solution together better.

Although I could not find any articles stating why alcohol began to be used instead of oils for holding the essential oils, I believe it has something to do with shelf life; as we know from Mueller, olive oil can turn rancid rather easily and have a rancid smell. Ethanol on the other hand has a very long shelf life and is much cheaper. This causes me to believe that the cologne industry would prefer to use ethanol as its solvent, as it is easier and cheaper to use, and this catalyzed oil’s exit from the world of colognes.

Cologne. As long lasting without oil? Probably not. As effective? I can only hope.

Other sources: http://www.ehow.com/facts_5690936_perfumes-colognes-made_.html