What is Eau de Cologne? (Chemistry and Uses)

• The name is French and literally translates to 'Water of Cologne'.
• It is named after the city of Cologne in Germany, where a perfumer named Johann Maria Farina invented the specific light citrus mixture in the year 1709.

All liquid fragrances are simply a mixture of pure fragrant essential oils (the smell) diluted in a solvent (usually Ethanol alcohol and water).

• Eau de Cologne (EdC) is defined as a very highly diluted mixture.
• It contains only 2% to 5% pure essential oils, mixed with a massive amount of alcohol and water.
• Because it contains so much alcohol, the alcohol evaporates very rapidly upon touching the warm skin, releasing a massive burst of scent immediately.

Because the concentration of actual oil is so low (under 5%), an Eau de Cologne is incredibly light and fresh, but it will generally completely disappear from the skin within 1 to 2 hours.

• It is originally designed not to be a long-lasting perfume, but rather a refreshing 'splash' used right after a morning shower.

To understand where it stands, here is the chemistry scale from weakest to strongest:

1. Eau Fraiche: 1% to 3% oil (Lasts 1 hour)
2. Eau de Cologne: 2% to 5% oil (Lasts 2 hours)
3. Eau de Toilette (EdT): 5% to 15% oil (Lasts 3-4 hours)
4. Eau de Parfum (EdP): 15% to 20% oil (Lasts 5-8 hours)
5. Parfum (Extrait): 20% to 40% oil (Lasts up to 24 hours)