Chalk & Liquid Chalk
Magnesium Carbonate chalk is used in climbing to dry sweat from the hands and increase grip. Loose chalk is available in blocks or as bags of powdery chunks. Chalk balls use a finer chalk wrapped in a muslin cloth, they're slightly less effective at drying your hands but won't spill chalk everywhere should you up-end your chalkbag. Liquid Chalk coats your hands with a thin layer and is the best choice for home bouldering walls, as there will be considerably less dust in the air.