Scientists Crack The Physics Of Coffee Rings

When the particles in a liquid are elongated, they slightly deform the surface of a drop of liquid, changing the forces inside the drop. When it dries, a solid layer is formed, rather than a ring.
When the particles in a liquid are elongated, they slightly deform the surface of a drop of liquid, changing the forces inside the drop. When it dries, a solid layer is formed, rather than a ring.