What does 'dry down' mean?

As with wine, cheese or music, greatness in perfume often means complexity.

If you regularly wear perfume, it should come as no surprise that your favorite scent unfolds in stages. The way you smell immediately after applying it, and then 20 minutes later and then 40 minutes later can be quite different, and this is by design. The people who created that scent chose its ingredients, which are basically essential oils, not only by their individual and combined aromas but also based on their relative evaporation rates.

The changing character of a perfume comes from the varying volatility of scent molecules. When you spray or dab on a fragrance, the first thing you smell is the combined effect of all of the scents in the product. Then, as some of those scent molecules evaporate and others stick around, the fragrance starts changing. Eventually, what you're left with is the scent of the longest-lasting, or least volatile, of the scent molecules included in your perfume -- and this final stage is called the dry down.

To be more specific, the scent of a perfume unfolds like this:

Although a scent is designed by perfumers to unfold in a particular manner, it is not a uniform evolution. And this is where things get more interesting.

Your perfume only smells like your perfume when it's on you. This is both good news and bad news.

Those scent molecules aren't only reacting with each other and the environment. They're also reacting with your skin, and everyone's skin is different. Your skin's particular absorption rate, for instance, affects how a perfume smells on you as it moves through its stages, because evaporation isn't the only way scent components disappear. They can also be absorbed. If your skin is relatively dry, it might absorb certain molecules faster than someone else's skin, meaning the exact combination and volume of scents present on your skin at any given time will never be exactly the same as what's on a friend's skin.

Other factors affecting a perfume's actual scent include your hormone levels, age, diet and which other skin products you use, because all of these factors play into the exact composition of your skin.

The good news is, no matter how many people are wearing your perfume, your scent is entirely unique. The bad news is, the perfume that smells amazing on your friend might smell absolutely awful on you.

In fact, a scent is not even static on a single person. Skin chemistry changes as we age, especially as hormones fluctuate. Major diet changes, illness and changing stress levels can also alter the way your perfume smells on you.

For this reason (and also, perhaps, to keep things interesting), it's important to periodically evaluate your perfume. Does it still smell appealing on you at every scent stage? Does the dry-down stage still last for a reasonable period of time, or do you find yourself having to reapply several times a day? You may find you need to make a switch to accommodate your changing body chemistry.

Just be sure to get a second opinion. Our noses get adjusted to a fragrance pretty quickly, making it difficult for us to judge our own scent. Ask a friend to help you evaluate your perfume, and tell him or her to be brutal. If you stink, it's better to find out now.

For more information on fragrances and skin chemistry, check out the links on the next page.