What Does Brushing Do When Curling?

Curling is a team sport played on ice and involves precision placement of eight granite stones in relation to a target area. Team members use large brushes in a process called "sweeping" to clear debris from the ice and to change ice friction levels that alter the course of the "rock," or granite stone. Sweeping allows the rock to travel farther and straighter.

  1. Origins

    • The sports of curling originated outdoors, and the sweeping practice in the game originated from the need to clear sticks, leaves, or frozen water droplets from the path of the stones that would accumulate between turns. As the sport evolved and was played in climate-controlled environments, players used sweeping because of its affect on the path of the rocks, allowing them to "curl," or take elliptical paths to the target.

    How it Works

    • Sweeping the ice directly in the path of the rock increases the frictional melting in that area in anticipation of the rock. This means the rock will experience less friction from the swept ice surface, as it has been slightly melted and wiped of debris. Technically, this can be described as decreasing the rock's rate of deceleration, allowing it to travel farther. Sweeping can never make a rock go faster, only farther.

    Curl

    • Rocks are pitched down the course in a predetermined rotation. The outside edge of the rock creates more friction because it travels a farther distance. By controlling the direction of the rock's rotation and controlling the level of friction on the outside edge of the rock, via sweeping, it is possible for teams to redirect the rock into hard to reach places on the court.

    Equipment and Technique

    • Traditional brooms used in curling were made of horsehair or hog's hair. Brooms made of synthetic materials such as Cordura became popular in the 1990s and became the standard. Experts debate whether the most effective sweeping stroke comes from rapid movement of the brush, or increased pressure on the brush head; a healthy use of both methods is thought to achieve best results.