How to stop a coffee stain using simple physics
(CBS) - In case you want to know how to keep those pesky, ugly coffee rings from forming on your coffee tables and desks, there's a solution - and it doesn't involve a coaster. (Though, you can use that too, I guess.)
"When a drop of coffee dries on a surface, its edges are held in place, preventing the drop from shrinking as it dries. Instead, it must flatten out while maintaining its original circumference," reports NewScientist. "This flattening pushes water - and the particles suspended in it - to the edges so that by the time the drop dries, most of the particles have bunched up to form a ring that's annoyingly hard to remove."
So how do you stop those coffee stains from happening? Just watch this cool video to learn about the mechanics of coffee rings (because everyone should know it, really). The trippy music is also intoxicating.
Physicist Peter Yunker and his colleagues at the University of Pennsylvania figured out how to keep it from happening. They examined the shape of particles in the liquid, as you'll see in the clip above, and realized that if they were torpedo-shaped (instead of spherical), they'd be "distributed evenly as [they dry]" and won't leave behind dark particles, says New Scientist.