Natural ice vs. artificial ice

Two ways to make ice

Not all ice is the same. Skating on a frozen lake is a completely different experience from skating in an ice rink. The difference lies in how the ice is formed and how it is maintained.

Natural ice forms through frost alone. That can be a lake, a canal or a meadow flooded in winter. Artificial ice is produced technically: a refrigeration plant cools a pipe system beneath the surface, onto which water is applied in thin layers. This creates a solid layer of ice even when temperatures are above freezing.

How artificial ice is made

Beneath an artificial ice surface lie many parallel pipes, usually in a concrete slab or in sand. A strongly cooled liquid flows through them, such as brine or glycol, or the refrigerant itself. Classic refrigerants are ammonia and increasingly CO2, because they are more climate-friendly than some synthetic refrigerants. The ice technician builds up the ice in many thin layers. In between, it is usually painted white and marked with lines and logos. Overall, indoor ice is only a few centimetres thick. More in ice technician and ice temperature.

The world's first artificial ice rink was the Glaciarium in London, opened by John Gamgee in 1876. The history of rinks is told in history of ice rinks.

How natural ice forms

Natural ice grows from the top down. In frost, the water surface cools first until a thin layer of ice forms. The colder and calmer it is, the clearer and smoother the ice becomes. Snow on the ice insulates it and slows its growth. If snow melts and refreezes, milky ice with less load-bearing capacity forms.

For natural ice rinks in places such as Davos or St. Moritz, areas are deliberately flooded and maintained without any refrigeration. Such rinks only work at altitude or in regions with reliable frost.

Differences when skating

• Evenness: artificial ice is level and has a controlled temperature. Natural ice can contain cracks, bumps and frozen-in leaves.
• Hardness: artificial ice is set warmer or colder depending on the sport. Natural ice is at the mercy of the weather; in hard frost it becomes hard and brittle.
• Maintenance: in rinks, a machine resurfaces the ice regularly – more in ice preparation. On lakes, at most the snow is cleared.
• Experience: natural ice offers wide open spaces and nature, often with routes many kilometres long. Skating tours on lakes and canals in the Netherlands and Scandinavia are legendary.

Famous natural ice venues

• Davos: its natural ice rink is one of the best known in Europe. Many speed skating world records were once set here.
• St. Moritz: the Olympia Bob Run for bobsleigh and the Cresta Run for skeleton are rebuilt from natural ice every year.
• Weissensee in Carinthia: since 1989 the frozen lake has hosted the Alternative Elfstedentocht, a long-distance race for thousands of skaters from the Netherlands, because the real Elfstedentocht in Friesland can only rarely be held.

Safety on natural ice

Natural ice can be life-threatening. As a rule of thumb, the German lifesaving association DLRG says still water should only be walked on once the ice is at least 15 centimetres thick, and flowing water only from 20 centimetres. In addition:

• Observe official approvals and warning signs.
• Never go onto the ice alone.
• Avoid dark patches, reeds, inflows and bridges, where the ice is often thinner.
• If the ice crackles or cracks, lie down flat immediately to spread your weight, then move back along your own track.

Artificial ice rinks do not have this risk. That is why almost all competitions take place on artificial ice.

Climate change and ice

Mild winters make natural ice rarer. Many natural ice rinks at lower altitudes can only open on a few days, and competitions on lakes are cancelled more often. At the same time, artificial ice is criticised for its energy consumption. Modern rinks therefore rely on efficient refrigeration plants, waste heat recovery – for swimming pools, for example – and better insulation. IceHub's rink search shows where you can find ice near you.