Why is sweeping in curling necessary? Isn’t the ice-sheet clean enough?

Question

Why is sweeping in curling necessary? Isn’t the ice-sheet clean enough?

In: Physics

Answer 1

Before the game starts the surface is sprayed with water, creating small bumps of ice where the droplets fell. This ~~increases~~ the friction on the stone.

By sweeping, the players are melting the bumps. They can make the stone go further or even slightly alter the trajectory.

Edit:
as u/hey_mr_ess has pointed out [it reduces the friction. ](https://theconversation.com/the-slippery-science-of-olympic-curling-we-still-dont-know-how-it-works-176463)