Whether you are watching a figure skating competition at the Winter Olympics or a professional hockey game on TV, you are looking at one of the great unsung marvels of the modern age — indoor ice. The fact that people can go skating in the summer, or that spectators can watch ice hockey in a warm arena, would amaze our ancestors. Let’s take a look at how a modern ice rink works.
The rink starts out as a thick slab of concrete with miles of pipe embedded in it. The pipes are filled with ice cold brine that comes from a large refrigeration plant. This plant uses the same kind of compressor technology that you find in your home refrigerator/freezer to create the ice cold temperatures. But it has been scaled up to massive size. The brine might be at 15 degrees F so the surface of the concrete drops below freezing.
Onto this frozen stone surface goes an incredibly thin mist of water — less than a millimeter thick. This layer freezes almost instantly and seals the concrete. Another thin layer or two goes on top. This forms the base for the first layer of paint.
Ice is usually painted white. In professional hockey, for example, the rules dictate that white is the ice color. Powdered white ice paint is mixed with water to create a thin liquid that is misted onto the surface.
Imagine a pipe four to eight feet long with misting heads aimed downward and a hose to pump in the paint. That is the “paintbrush” for laying down the paint on the ice surface. This paint freezes and is then covered with several more clear layers of water to seal it.
A rink will use deionized water to remove any salts or impurities from the ice. This purified water helps to make the ice crystal clear for the logos and lines, and also makes the ice faster.
Next comes all of the lines, markings and logos. These can be made of thin vinyl sheets or they can be hand-painted.
Several layers of water mist seal them in, and then it is time for the ice surface. This is added as a series of a dozen layers or more to create a surface that is about an inch thick.
The thickness is important. If the ice is too thin, the skates might gouge through into the paint layers or right down to the concrete. If it is too thick, it is hard to precisely control the temperature of the ice surface. And that is important because different skaters like different temperatures.
For example, a figure skater wants relatively soft ice, perhaps at 27 degrees F. This gives the surface a little more grip for precision turns, and also prevents cracking after a big jump. Hockey players want harder ice, perhaps at 25 degrees F. In a hockey game you have so many players on the rink that soft ice can get gouged and choppy.
Keeping the surface of the ice at the precise temperature that skaters prefer is not trivial, because the conditions inside the arena are changing constantly. When you fill up an arena with thousands of warm, breathing fans, the temperature and humidity of the air changes quickly. The building’s ventilation system and the ice managers have to adjust to keep the surface perfect.
By the time it is complete, the whole process of building the ice might take a week and use 15,000 gallons of water. Temperature probes feed data back to control systems that adjust the temperate of the concrete slab and therefore the ice surface.
In many venues where professional hockey is played, the surface of the hockey rink may need to be converted into a basketball court or even an indoor monster truck track.
There are two options in these situations. The first is to cover the ice with thick foam insulation and then assemble the hardwood basketball court like a jigsaw puzzle on top of the foam.
In the case of a monster truck show or a circus, the ice is removed. The concrete slab is heated to quickly melt the ice. After the show, the whole weeklong process of constructing the ice is repeated.