Why put chalk (or blue) on billiard cues?
Whether you call it chalk or blue, it's an essential accessory. And for a simple reason: putting blue on the cue tip (the end of the cue that hits the cue ball) gives it better grip.
And so? And so making shots easier will put spin on the cue ball as much as preventing false cues (slippage of the cue tip on the ball that can cause the shot to miss).
The pro tip
Most people rub the chalk on the tip of the tail, which actually prevents the chalk from depositing. Instead, stroke the tip with the chalk, checking that the blue settles everywhere.
Good to know: the impact of chalk on marbles
With each shot, a little resin is deposited on the ball. Eventually, you'll need to think about polishing the balls (with an appropriate machine, which can be found in billiard clubs, or with a suitable product).
On the practical side, remember to put your blue head up when you place it on the billiard table, so as not to dirty the table. There are also magnetic chalk holders to keep your chalk close at hand throughout your game.
