Why Do They Sweep? The Physics of Curling Explained

You’ve seen it on TV: one person slides a stone, and two others furiously scrub the ice in front of it while screaming “HURRY!” It looks chaotic, but it is actually one of the most precise displays of physics in sports.

So, why do they sweep?

1. The Ice isn’t Flat (It’s Pebbled) Unlike the smooth ice used for hockey or figure skating, curling ice is sprinkled with water droplets that freeze into tiny bumps. This is called “pegging” or “pebble.” If you just slid a stone on flat ice, the bottom would create a vacuum and it wouldn’t go anywhere. The stone actually rides on top of these tiny pebbles.

2. Friction = Heat This is where the sweeping comes in. When the sweepers scrub the ice with their synthetic brooms, they generate friction. Friction creates heat. This momentary heat slightly melts the very tops of those ice pebbles, creating a microscopic layer of water.

3. Water is Lubricant That tiny layer of water acts as a lubricant, reducing the friction between the stone and the ice. This does two things:

• Distance: It allows the stone to glide further (by up to 2-3 meters!).

• Direction: It makes the stone curl less (it stays straighter).

So, when the Skip (the captain) yells “SWEEP,” they usually want the stone to travel further or stop curling too much. When they yell “WHOA” or “OFF,” they want the friction to return so the stone slows down and curls more.

The Ultimate Ice-Free Experience at The Curling Club

Enjoy all the competitive thrill of curling without the chill! Our lanes are completely ice-free, meaning you don’t need specialist shoes or heavy equipment. Best of all? No sweeping is required. We’ve removed the frantic cardio so you can focus entirely on your aim, strategy, and the Alpine atmosphere.

Join us for the perfect winter social at our locations in Manchester and across London (Vinegar Yard, Chelsea, and Canary Wharf).