Have you ever wondered how they change the floor quickly between a basketball game and a hockey game?
The cement floor has a bunch of freezer tubes of ethylene glycol (antifreeze). To make the rink, the floor is cooled to zero degrees. An eighth of an inch of water is then sprayed on and freezes. The ice is painted white with fine talcum powder and then another half inch of water is sprayed on to freeze. The whole process takes about 12 hours. Removing the ice means heating the tubes until the floor hits about 68 degrees (20 c) and the sheet of ice pops loose. A tractor with a blade breaks up the sheet and shoves the pieces into a pit. The heated tubes dry the floor rapidly and the basketball boards are laid on top. (From The Slice, by Katherine Dunn)