When pouring a liquid, what determines if it pours out nicely or dribbles down the side of the original container?


I hate that!

In: Chemistry

Water is a polar molecule (which means it likes sticking together and with other polar molecules)



In this case, depending on the material the container is made of, it’ll have a certain tendency to want to stick to that as well, hence dribbling on the side. The attraction it has is fairly weak, so if you increase the angle, or the amount of water you are pouring, that can overcome it.

It seems it’s a more complicated phenomenon than many people realize. [Here’s an article on some research just this year on how the interaction between “hydrodynamic suction” and wetting influences whether the pour detaches cleanly or dribbles.](https://arstechnica.com/science/2019/05/dribble-no-more-physics-can-help-combat-that-pesky-teapot-effect/)