Commercial Coffee Machine experts Cimbali reveal – why it is easier to spill your coffee than your beer this Christmas!

Cimbali reveal why your coffee is easier to spill than your pint

With Christmas and New Year celebrations making bars, restaurants and cafes busier than usual, carrying yours and your friend’s full drinks back to your table can be even more treacherous than normal!

Anyone who has carried a coffee through a busy café will know just how easy it is to spill the drink over the sides of the cup. But carrying beer – even if you have had one too many….. is so much easier!

Now scientists think they know why, and it’s all to do with the beer’s foamy head! Researchers have recently studied the waves created by people carrying different drinks to demonstrate that foam reduces sloshing, and dampens the waves themselves. This knowledge could one day be used to work out better ways of transporting huge quantities of liquid more safely and efficiently.

Using a high-speed camera, the study set out to prove that coffee is tricky to carry, whereas beer is so much easier. It filmed a moving stage and fluid with, and without a head of foam, and the creation of sudden movement. The research showed that just a few layers of bubbles are all that is needed for the effect to work, and it doesn’t matter if it is foam on a pint of Guinness or Heineken – it reduces the sloshing and is very efficient at damping the waves. The foam is efficient because of viscous dissipation where the ‘thickness’ or viscosity of a fluid takes energy from its motion and transforms it into heat energy. As the waves form and the beer travels, the foam on the beer rubs against the walls of the glasses, and this rubbing causes a lot of energy, which results in damping. The effect is not seen in cups of coffee, which do not have any foam on top of them. That’s why coffee spills more easily than beer. To conclude, the more foam a drink contains, the less likely it is to slosh around.

Although this time the liquid was beer, the study could one day help to create better ways of transporting large quantities of liquid more safely, particularly industrial loads, in the form of cargo.

So, this festive period when you are crossing a busy room with a few beers in your hand, trying not to drop them – be thankful that it’s not hot coffees you are carrying!