Sept. 24, 2003

A Perfume's Changing Aroma

Expensive perfumes of today are a blend of between 200 and 500 different ingredients, some of them only traces. Natural ingredients from flowers and herbs are extracted by pressing leaves and petals between layers of fat. This in an expensive and labor-intensive process which produces "essential oils." Once an essential oil is in a fat, it can be dissolved in alcohol to make perfume.

I. Peterson

The person who creates a great perfume is trained to tell the differences between hundreds of fragrances and fragrance blends. This high-paying and important job is held by someone called a "nose." Legendary noses have been known to not only tell the difference between different rose oils, but where the roses came from, when they were grown, and where the oils were processed.

The essential oils that are combined to make perfumes not only smell different from each other, but also evaporate at different rates. This means that once a perfume is exposed to the air, its smell changes as time passes. How does perfume change over time? This experiment will show you.

Materials and Equipment:

• strips of coffee filter paper, 1/2 inch wide and about 3 inches long
• perfume, cologne, or aftershave lotion
• pen or pencil
• clock

Method of Investigation:

1. Dip the end of a strip of filter paper in your perfume sample. Write the time on the other end of the strip. Set the strip aside.
2. After ten minutes, repeat this procedure with a second strip of filter paper. Smell your two strips. Be sure and refresh your nose between sniffs by sniffing your sleeve.
3. Repeat your procedure again twenty minutes later. Compare your freshly dipped sample with the one that is now twenty minutes old and one that is thirty minutes old. Make another test one hour after you started, then three hours, or set your own time schedule.

Observations and Suggestions:

The aroma you first smell is from the oils that evaporate first. These oils are called the "top notes" of a perfume. Just after the top notes have evaporated, the aroma left behind is the "body" of the perfume. The fragrance that remains after several hours is the "dry down." This part of the perfume contains the slowest evaporating oils.

Perfume on your skin behaves differently from perfume on filter paper. Your skin chemistry mixes with a perfume and alters the smell. Test this idea by sniffing the perfume on the filter paper and the perfume inside of your wrist.

Perfume on your warm skin also evaporates faster than perfume on filter paper. It evaporates fastest when placed on "pulse points" like the wrist or inside of the elbow, where the blood supply is closest to the surface. Try the time test on your skin. Compare the smells after the same time intervals with samples on paper. Compare smells of perfumes placed on the back of your forearm. Experts says that perfume usually lasts about four to six hours on your skin.

One problem is that your nose adjusts to the fine perfume odor as it would to any odor, pleasant or unpleasant. After a while, you think that the perfume you're wearing has disappeared. It hasn't. You can't smell it any longer, but it's still there.

Used, with permission, from See for Yourself: More Than 100 Experiments for Science Fair Projects by Vicki Cobb. Published by Scholastic Reference. Copyright © 2001 by Vicki Cobb (http://www.vickicobb.com ).

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