The teacher asked Joe whether he stole three atoms of sodium.

Joe said, "Na Na Na!"


Why cold cream is so cool to touch

Cold cream gets its name from the cool feeling that you get when you apply it on your skin. It is used to cleanse the skin, remove makeup and soften the skin. They are also used on sunburnt skin. How this cream manages it is a cool bit of chemistry.

The first cold creams

The first cold cream was invented over a hundred years ago by the Greek physician called Galen. Women during Galen’s time were not too different from the women of today. They wore heavy make up and needed a way to remove this.  He invented the cream using a variety of ingredients such as jojoba oils, alcohol and glycerine.

The ingredients of cold cream

Cold cream is a mixture of water with certain fats. One of the most popular being bees wax. In addition there are a variety of scenting agents to provide a pleasant smell. The first cold cream was made of beeswax, water, olive oil and rose petals.  Today’s cold cream replaces the olive oil with mineral oil and other oils that do not spoil quickly. The most popular oil is jojoba oil, derived from a shrub native to southern Arizona, Southern California and Mexico. Borax in cold creams gives it its pure white colour.

What makes cold cream cold?

Cold creams are called ‘cold’ cream because of ingredients like alcohol that are highly volatile. These substances leave a cooling effect when they evaporate. Evaporation is an endothermic process that requires heat. The warmth of your skin is enough for the cream to start to evaporate. This process is similar to that of perfumes where there is a presence of alcohol as well. When applied to skin the alcohol in the cream being highly volatile uses the heat of the body to evaporate and thus gives you a cooling effect.

When applied to skin the alcohol in the cream being highly volatile uses the heat of the body to evaporate and thus gives you a cooling effect.

Alcohol used in cold creams

The most popular alcohol that is used in this cream is ethanol. This has a low boiling point and a high vapour pressure. The high vapour pressure of a liquid at a fixed temperature, the liquid has a greater tendency to escape to the gas phase. The chemical characteristics of ethanol ensure that it evaporates faster than water on your skin.  The alcohol content makes this cream so easy to apply and improves the perfume quality of the mixture.

Tags :     Everyday Chemistry     Cold Cream     Vapour Pressure     Volatility     Evaporation     Vaporization     Endothermic    


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