Chalk, or magnesium, is used in climbing to improve grip by drying out the climber's hands. Chalk absorbs moisture and reduces perspiration and is available in various forms: powder, block, ball or liquid. It allows climbers to concentrate on their performance without worrying about slippery hands. If you're heading outdoors and use liquid chalk - please choose a resin-free option, as resin clogs and polishes the rock and destroys the holds.