A drop of water with added elastic polymers falls onto a surface that repels water as well as a lotus leaf. On impact, the liquid pushes into microscopic pits, stretching out a thin tail, like a stretched rubber band. Then elasticity causes the tail to snap back, but inertia and gravity, described by Newton, stretch it even more. Eventually, the tail tip balloons into a sphere, and the entire drop bounces off, like a released rubber band. This process was captured using photometry — a highly sensitive technique that detects the tiniest light changes.

By changing the surface texture, the size of its bumps and pits, you can control the tail shape and the bounce. The paradox is that these very irregularities, which should hold the liquid, make it bounce. This discovery will be useful for self-cleaning glass, water-repellent clothing, and precise inkjet printing — ink drops will hit their target exactly.