Colognes In Hot Cars: Do They Go Bad?

Many people like to keep a bottle of perfume or cologne in their car for a quick refresh on the go. However, this may not be the best idea as the delicate chemistry of the fragrance can be altered by extreme changes in temperature. The ideal temperature for perfumes is between 12°C and 22°C, while a car's temperature can reach up to 46°C on average and even go above 93°C. This can cause the perfume to lose its top notes and smell dull or off, or even evaporate or break down over time.

Heat and oxidation

Heat can cause the ethanol-water solvent in cologne to reach its boiling point, which will cause the cologne to eventually evaporate. This is more likely to occur when the cologne is exposed to direct sunlight and high temperatures for extended periods of time. The ideal temperature for storing cologne is between 12°C and 22°C.

Oxidation occurs when oxygen interacts with the cologne, causing it to break down and lose its original scent. This process is accelerated when the cologne is exposed to heat and sunlight, as well as when the bottle is shaken or vigorously moved, such as in a car.

To prevent heat and oxidation from damaging your cologne, it is recommended to store it in a cool, dry, and dark place, such as a closet, rather than in a hot car. Additionally, keeping the bottle sealed and avoiding half-full bottles with a lot of trapped air can help slow down the oxidation process.

Sunlight and UV rays

The delicate chemical balance of a fragrance can be altered by extreme temperature changes. The top notes of a cologne or perfume are usually fresh, light, or citrusy. However, long-term exposure to heat and sunlight can cause these fragrances to "turn off," resulting in a stronger alcohol or vinegar scent.

In addition to temperature, sunlight, and UV rays, the constant movement and shaking of a car allow air to mix inside the bottle, accelerating the breakdown of the scent and reducing its lifespan and quality.

To maintain the integrity of your cologne or perfume, it is best to store it in a cool, dry, and dark place, such as a closet, rather than in a car.

Shaking and oxidation

Oxidation is a chemical process that occurs when a substance is exposed to oxygen, which can cause the substance to change its properties. In the case of cologne, oxidation can cause the fragrance to evaporate and lose its original scent, or turn dull or off. This is why cologne should be stored in a cool, dry, and dark place, such as a closet, rather than in a car.

While heat is not the biggest enemy of cologne, it can still cause damage over time. High temperatures can alter the molecular chemistry of cologne, causing it to lose its top notes and smell more like alcohol or vinegar. Direct heat creates a negative chemical reaction, and over time, the cologne will either evaporate or break down.

It is important to note that a sealed, factory-packed bottle of cologne is unlikely to be damaged by being left in a car for a short period of time. However, if the bottle is unsealed or half-full, the heat and oxygen can cause the scent to evaporate more quickly.

Flammable liquids

Colognes and perfumes are flammable liquids. Their base ingredients, typically alcohol or ethanol, make them easily ignitable. The flashpoint of a scent is the temperature at which a liquid releases vapour that can ignite. The flashpoint differs according to the type of alcohol used in cologne preparation.

Most perfumes contain up to or more than 24% ethyl alcohol by volume, with a low flashpoint, usually about 16 degrees Celsius. This means that even at room temperature, the fragrance alcohol can evaporate and burn when exposed to an open flame or spark. Pure ethyl alcohol has a flashpoint of 13 degrees Celsius, but when mixed with water, its flashpoint is lowered.

The ethanol-water solvent used in most perfumes is a great diffuser but is also a flammable liquid. If a perfume reaches its flashpoint and an ignition source is applied, it will catch fire.

Perfumes are considered a flammable liquid, hazard class 3. There are also three packing groups (PG) that indicate the degree of danger within most hazard classes. Based on their higher flashpoint and boiling point, most perfumes are considered a Packing Group II or III.

Perfumes are considered hazardous materials and must be shipped in compliance with strict guidelines. This typically involves packaging the perfume in specific materials and labelling the package correctly.

Cabin temperature

A car's cabin temperature can rapidly reach extreme levels, often exceeding 116°F (46°C) and sometimes even surpassing 200°F (93°C). These high temperatures, coupled with sunlight exposure and UV rays, can cause the cologne to deteriorate quickly. The ideal storage temperature for perfumes is between 54°F (12°C) and 72°F (22°C), which is significantly lower than the temperature inside a parked car.

The heat, sunlight, and UV rays can cause the fragrance to evaporate, lose its original scent, or even discolour. Additionally, the constant shaking of the bottle during a car ride can accelerate the oxidation process, further damaging the cologne. While a sealed bottle may withstand the heat for a short period, leaving cologne in a hot car for an extended time can negatively affect its quality.

To maintain the integrity of the cologne, it is advisable to store it at a neutral temperature, not in a hot car. Transferring a small portion to a separate container for convenience is a better option than keeping the entire bottle in the vehicle.

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