Diagram of the layers of an ice rink manufactured for ice skaters. Ice layers: The skating surface is formed with as many as 24 layers of ice and paint. Warm water is used for the top layers because it contains less dissolved air, and can produce a denser, harder, frozen surface.

1. Skating surface: The surface is built up from thin layers of ice to a depth of less than 2 cm. The ice can be as cold as –8°C. The temperature and the hardness of the ice are controlled by tiny changes to the temperature of the underlying concrete layer.
2. Chilled concrete slab: The temperature is controlled by cold salt water, which is pumped through pipes embedded in the slab. The salt water remains liquid because its freezing point is lower than that of pure water.
3. Insulating layers: These layers prevent heat from rising up into the concrete slab from the warmer sand layer underneath.
4. Sand layer: To prevent the gravel layer from freezing, which could damage the rink structure, the sand layer is kept at a temperature above 0°C.
5. Gravel layer: This layer provides the foundation for the rink.