Expert: Profile Closed - 1/26/2010

Question
Hi there Mr.Maxwell! How are you?! I hope all is well! There's one more question I have for you pertaining to fragrances and the odor around them. When one applies a fragrance, it picks up the air around it, correct? What if the air around has an unpleasant odor such as food cooking (fish,meat, etc..) or something else, and a fragrance is applied there? Would that affect the fragrance in any negative way? Thanks! Hope to hear from you soon! Take great care!  

Answer
Hi there, lovely to hear from you again, and I hope you are well?

When a fragrance is released, it doesn't normally pick up air, what happens is that it "diffuses" amongst the gas molecules that make up the air in the room.

Diffusion is a well-known effect in science, where a substance spreads out to fill its surroundings. Air is constantly moving, so the fragrance molecules that are released as a concentrated cloud gradually spread out and mix evenly with the air in the room. You can model this process with a large (pint) glass and some ink. Fill the pint glass with cool water, and carefully add a drop of ink to the glass. Don't stir it, move it or anything, just leave it standing on the side for several hours. The concentrated ink is jostled around by the water molecules until it spreads out to form an even, dilute solution across the whole glass. In this model, the ink is like your fragrance, and the water in the glass is like the air in the room.

As to other odors; as I've said before, it's quite rare for other substances to actually react chemically with fragrances because they are stable - they have to be, given that they are stored in concentrated ethanol. However, other smells can affect how fragrances are interpreted by our bodies.

Smell is a sense triggered when a molecule fits in to a chemical receptor in the nose and sets off a nerve impulse to the brain. Fragrance molecules are chosen for their acute smell, and so they tend to be very good at triggering of a "smell response"; so in the first instance if you spray a fragrance in an atmosphere of bad odors, the first effect will be to mask the bad odor with the pleasant smell of the fragrance.

This isn't a chemical reaction between the fragrance and the odor, it's simply that the fragrance molecules are present in high numbers and trigger better responses in our nose than other odors. As the fragrance diffuses and spreads out, there are less fragrance molecules in the immediate area, and other odor molecules can start triggering their responses, so you go through a "confused" stage where your nose is receiving a mixture of dilute perfume molecules against a background of other odor molecules; there are interpreted as a unique smell in your brain, and generally aren't all that pleasant (think rose-water and rotting fish as a mixed odor!). As the perfume diffuses completely, the amount in the room  drops and drops until there are only the unpleasant odor molecules left, and the smell-response triggered is that of an unpleasant smell.

Hope that helps; in summary, there is unlikely to be a chemical reaction between most fragrances and most common odors. The initial effect of spraying perfumes in to an area of bad smells will be to mask the smell as the fragrance molecule takes up the receptors in our noses. However, as the fragrance diffuses and disperses, the sensation from our nose changes to a less-pleasant "mixed smell" and then eventually goes back to being a pure bad odor.

To bring out the best of your perfumes, therefore, clean air that doesn't have any other smells (including things like air-fresheners as well as bad smells) is the best background. Every other odor in the room is in a sort-of competition with the fragrance to be the first to get to your nose and trigger a smell-response; eliminating other odors and giving only a plain backgrounds means that your nose will only be responding to the fragrance, and not to a mixture of smells.

Hope this helps! best wishes, and nice to hear from you again.