Dilution classes of perfume
In the 20th century, the term took on a second meaning. Fragrance companies began to offer lighter, less concentrated interpretations of their existing perfumes, making their products available to a wider range of customers. Guerlain, for example, offered an Eau de Cologne version of its flagship perfume Shalimar. In contrast to classical colognes, this type of modern cologne is a lighter, diluted, less concentrated interpretation of a more concentrated product, typically a pure parfum. The cologne version is often the lightest concentration from a line of fragrance products.
Classical colognes first appeared in Europe in the 17th century. The first fragrance labeled a "parfum" extract with a high concentration of aromatic compounds was Guerlain's Jicky in 1889. Eau de Toilette appeared alongside parfum around the turn of the century. The EdP concentration and terminology is the most recent. Parfum de toilette and EdP began to appear in the 1970s and gained popularity in the 1980s.
Historically, women's fragrances tended to have higher levels of aromatic compounds than men's fragrances. Fragrances marketed to men were typically sold as EdT or EdC, rarely as EdP or perfume extracts. This is changing in the modern fragrance world, especially as fragrances are becoming more unisex. Women's fragrances used to be common in all levels of concentration, but today are mainly seen in parfum, EdP and EdT concentrations.
Perfume oils are often diluted with a solvent, though this is not always the case, and its necessity is disputed. By far the most common solvent for perfume-oil dilution is alcohol, typically a mixture of ethanol and water or a rectified spirit. Perfume oil can also be diluted by means of neutral-smelling oils such as fractionated coconut oil, or liquid waxes such as jojoba oil.
The conventional application of pure perfume (parfum extrait) in Western cultures is at pulse points, such as behind the ears, the nape of the neck, and the insides of wrists, elbows and knees, so that the pulse point will warm the perfume and release fragrance continuously. According to perfumer Sophia Grojsman behind the knees is the ideal point to apply perfume in order that the scent may rise. The modern perfume industry encourages the practice of layering fragrance so that it is released in different intensities depending upon the time of the day. Lightly scented products such as bath oil, shower gel, and body lotion are recommended for the morning; eau de toilette is suggested for the afternoon; and perfume applied to the pulse points for evening. Cologne fragrance is released rapidly, lasting around 2 hours. Eau de toilette lasts from 2 to 4 hours, while perfume may last up to six hours.
A variety of factors can influence how fragrance interacts with the wearer's own physiology and affect the perception of the fragrance. Diet is one factor, as eating spicy and fatty foods can increase the intensity of a fragrance. The use of medications can also impact the character of a fragrance. The relative dryness of the wearer's skin is important, since dry skin will not hold fragrance as long as skin with more oil.