Perfumer's Notebook: Stability of Fragrance Profile

An essential feature of any well compounded fragrance is its property of maintaining a constant profile during its exposure. This applies to fragrances applied to the skin, as with colognes or perfumes, or exhibited on the surface of toilet soaps. Marked change in profile during exposure may occur through lack of attention to relative evaporation rates of the perfume components. The rate at which a substance evaporates is, of course, a direct function of its vapor pressure, i.e. its tendency to change from liquid or solid to a gas.

Only limited information is available pertaining to vapor pressures of perfume chemicals and oils. We can readily determine the boiling points of simple, stable chemicals, such as phenyl ethyl alcohol, benzyl acetate, citronellol, etc., and we know that most solids, such as coumarin and the musks, evaporate very slowly. Generally evaporation rates at use temperatures parallel the boiling points, but for many substances, association and other phenomena affect the temperature/volatility curves.

The perfumer, and especially the novice or apprentice, will assist his development and increase his capability in the use of aroma materials by determining for himself the relative volatilities of the materials he uses. The methods can be simple.

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