Question of the Month: Why does coffee form ring-shaped stains?

Every morning it’s the same: A few drops of coffee end up on your table. And once they dry, they form ring-shaped stains. But why? This problem is related to the question how to build tomorrow’s communication systems. Some of you might remember your grandma’s coffee pot, which had a sponge attached to the spout. … Continue reading Question of the Month: Why does coffee form ring-shaped stains?