Pebbling refers to when a thin layer of water is sprayed over the surface of a curling sheet. This occurs before every game in a competition in order to prepare the surface for optimal curling. It is called pebbling because as the water dries, it forms small pebbles of ice on the surface of the sheet. These pebbles are what gives the stone its curl. The pebbles also create some friction between the stone and the surface of the ice, ensuring that the stone doesn't move too fast or too far. The movement of brushing smooths out these pebbles, allowing the stone to move across the sheet.
Pebbling can be done by several different machines. They range from as simple to a hose with a sprayer on the head, to a complex bottle and sprayer system. For higher levels of competition, specific machines are used that are set to exactly the right pressure in order to create the best pebbles. Similar to a machine that sprays weed killer, the equipment consists of a plastic container of water attached to a pressurized hose. Ice makers will walk around with it to ensure the entire surface of the sheet is covered. Pebblers can be bought online for anywhere from $250 to $600.
In order to create the best pebbles on the ice, those pebbling must make sure they have several things. They must have good water quality to ensure accurate pebbles, as well as a specific water pressure as they spray. Too high or low water pressure will make the pebbles too small or too big, causing problems for the curling stone. The temperature of the water must be cold enough that it freezes when it touches the ice, and cannot be too warm, or it might melt the surface of the sheet. All of this considered, the job of the pebbler is difficult. They have to make sure all of the factors are lined up to ensure the ideal curling surface.