In 1892, a man named William Painter faced a straightforward problem:
“How can we keep drinks sealed, fresh, and easy to open?”
His solution was a metal cap designed with exactly 21 ridges. Not 20. Not 22.
Twenty-one was the magic number that ensured the seal was airtight without risking damage to the bottle or your fingers.
Today, after billions of bottles, the design remains unchanged. There have been no redesigns and no gimmicky marketing—just pure, reliable functionality.
UX Lesson: The best designs don’t draw attention to themselves. They effectively solve a real problem so well that they remain invisible and unchanged.
