Equipment
Rocks - Curling rocks (or stones) are made of granite, mostly from Scotland or Wales, and weigh between 38 and 44 pounds. They are about 6 inches tall and 11 inches in diameter. Very little of the rock actually touches the ice. The bottom of a rock has a cavity about 6 inches wide. Rocks slide on the outside edge of that cavity, known as the running surface. Modern stones have plastic handles that are bolted to the rock. Special handles with built-in hog line sensors are used in high level competitions to determine if a curler has released the rock before the near hog line.
Rocks curl because of a combination of factors, and articles in scientific journals debate the physics of curling rocks. Whatever the ultimate reason, rocks do curl as much as 4 feet from release to stop on well prepared ice. The direction of curl is always opposite the direction of the trailing edge of the rock: that is, a rock rotating clockwise will curl from left to right, and a rock rotating counterclockwise will curl from right to left. The skip will estimate the amount of curl expected for a particular shot and adjust his/her target placement accordingly. Anticipating this curl is perhaps the most important part of the game, especially so at high levels of competition.
Broom - Curling brooms are used for two purposes: for sweeping and as a stabilizing device when delivering the rock. Brooms used for sweeping are made of either hair or a synthetic pad. Occasionally you will still see curlers use corn brooms during delivery. Other stabilizing devices are becoming popular, especially for new curlers.
There is no good scientifically verifiable theory to explain the effects of sweeping in curling. However, it is apparent that sweeping transiently and slightly decreases the friction of the ice surface, allowing a moving rock to retain its speed longer and reducing the ability of the stone to dig in and curl. So sweeping makes the rock travel farther (not faster!) and "straighter" (it will continue more in the direction in which it is already traveling). If a rock has begun to curl sharply, sweeping will make it travel straighter and farther in the direction it is going when you begin to sweep: you cannot straighten in "back on course" by sweeping.
Shoes - Curlers wear specially designed shoes. The sole of one foot has a layer of Teflon which enables the curler to slide when delivering the stone. The sole of the foot placed in the hack is made of rubber which provides traction on the ice. When sweeping, many curlers place a gripper over their slide foot to provide additional traction. Right-handed curlers slide on their left foot; left-handed curlers on their right foot.
