Other Equipment

Chalk and the mechanical bridge are always used in pool. The mechanical bridge is used for tough shots, where the player needs extra length. Chalk is rubbed on the top of the cue stick to provide grip.

Mechanical Bridge

The mechanical bridge is used to extend a player's reach on a shot. It is a stick with a grooved metal, or sometimes plastic, head in which the cue stick sits on. It is sometimes referred to as the rake, bridge stick, or bridge. In Europe a rest is used. The head of the bridge can vary in design. In Italy, players use a longer thicker cue stick instead of a mechanical bridge. In snooker mechanical bridges come in three different forms. They depend on the players style. The spider bridge has a raised arch that goes out about 12 cm, and three grooves for the cue stick. The standard cross is the standard bridge. The giraffe has a raised arch that goes out about 15 cm and has one groove.You can also use screw on cue stick extensions.

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Chalk

Chalk is used in all billiards style games. Its main purpose is to provide the player more grip on the ball. You rub chalk on the tip of the cue stick, and that allows the player more grip on non center shots, and is used to put spin or curl on the ball. Chalk that is used isn't real blackboard chalk, it is a different kind. Chalkboard chalk is calcite, and Pool chalk is silicate. Cue tip chalk was invented in 1897, by pool player Will Spinks, and chemist Will Hoskins. The chalk is made by crushing silica and aloxite into a powder and glued together. Harder, dryer chalks are the best.When chalk was first introduced to American players, it was called "putting English on the ball." 

There is also another type of chalk, hand chalk. Hand chalk is used to provide the player with a more smoother stroke on a shot. Many players nowadays prefer to used a pool glove instead of hand chalk, due to the messy mess the chalk can make. The buildup of the chalk particles on the table cloth can result in affecting ball movement. Some players use the lubrication method. Which is when a player mixes the hand chalk with saliva, to create a chalky paste which is a lubricant for the cue stick. This method was invented by professional pool player, Hal "Spitty-Smitty" Smith.

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Here is an article with much more info on certain chalks.

Here is a video that shows you how to put on pool chalk.