Understanding the physics of coffee stains

Why does coffee leave a ring when it dries, and why is it so difficult to wash out of clothes? Here’s looking at the science behind the stain.

Coffee is a wonderful beverage, brightening up your morning and keeping you mentally alert all day. Even the aroma of coffee is quite energising. It is consumed differently around the world, whether with milk, sugar or just in plain hot water. Whichever style it is prepared in, it pleases the palate and awakens the senses.

But this sensual beverage also has a big downside – it leaves tell-tale stains that adhere to clothes like superglue! Coffee stains are often light brown in colour, and tough to wash out even with many washes. You can get coffee all over yourself when you spill it on your clothes, or when you inadvertently place an overfull coffee cup on the tablecloth. It leaves behind a stain that is dark around the edges and translucent in the centre.

The physics of coffee stains explained

Research shows that beverages like coffee leave stains differently than other beverages like juice and water. If you let spilled coffee dry on a surface, and another liquid like fruit juice dry on another surface, their stains are different from each other. The coffee stain is rimmed dark around the edges, while the fruit juice leaves an even stain.

This happens because the molecules in coffee, say scientists, are completely spherical and active. The molecules in other beverages are oblong and less volatile. As the stain dries, the coffee stain starts drying around the edges faster than the centre. To make up for the loss of molecules around the rim, more molecules from the centre rush to take their place. This results in a concentration of molecules around the edges, and an ‘emptying’ of molecules in the centre. The result is a dark edge in the coffee stain that is sharper in definition than the centre.

How to remove coffee stains

The stubbornness of coffee stains is down to their reactive molecules. These molecules are able to bond quickly with molecules in clothing fibres. Cotton, linen, jute and canvas are particularly vulnerable to staining, while heavily bonded fabrics like wool and polyester are not.

Moving quickly is the key to effective coffee stain removal. The stain must not be allowed to dry on the fabric. If it is about to dry, it must be moistened periodically with water to buy time for stain removal.

Use a good stain removing product like Vanish powder or liquid to banish coffee stains from your clothes. If the stain is dried or old, you can soak the garment in water adding Vanish to it as directed. If the stain is new, blot it out with a paper towel, and apply Vanish to the stain directly.

Coffee stains are a thing of the past with Vanish by your side!