The Ice

Image courtesy © 2005 Torino 2006/LaPresse.

A big part of the Winter Olympics happens on ice. The ice events include figure skating, hockey and speed skating. In speed skating especially, the ice is incredibly important. The better the ice, the faster the athletes can go. On the best ice, the skaters can break world records.

A speed skating rink starts with a huge, perfectly smooth slab of concrete. Buried in the concrete, are miles and miles of pipes. Ice-cold saltwater flows through the pipes at -5 degrees F, and it cools the slab down well below the freezing point of water. When you mix a salt like calcium chloride into water, you lower the water's freezing point. There's a point, called the Eutectic point, where you have dissolved as much salt as possible into the water. At the Eutectic point, water mixed with calcium chloride freezes at about -8 degrees F. Rinks use saltwater in the pipes because salt is very inexpensive and also relatively safe. It is not an environmental disaster if a pipe breaks and spills a thousand gallons of salt water. A typical speed skating rink uses 200,000 gallons of saltwater to keep the concrete slab cool.

Now your job is to create perfect ice on top of this ice-cold slab. You start with perfect water. You filter the water so that there are no salts, particles or liquids of any kind mixed in with the water. Using this ultra-pure water, the goal is to build up a layer of ice about 3/4 of an inch thick. You do this by building up about two dozen extremely thin layers. The first layer of water is just a mist that seals the concrete. Then there is a layer of water-based paint to give the ice a uniform white color. Then there is a layer to seal the paint. Now the ice team floods the surface with a thin layer of water that freezes almost immediately. They do this over-and-over until a perfectly smooth sheet of ice covers the slab.

Image courtesy © 2005 Torino 2006/LaPresse.

But that is only one small part of the quest for perfect ice. Technicians worry about everything. For example, they worry about the air temperature in the building, so they install huge air conditioners (in case it is too hot outside) and heaters (in case it is too cold) so the air in the building has almost exactly the same temperature as the ice on the floor. Then they install huge dehumidifiers to keep the humidity in the arena down. And they use giant air filters to remove any dust from the air. If dust settles on the track it will slow down the competitors on the ice.

When they resurface the ice, they use a special kind of water with a little soap-like fluid mixed in. The soap makes the ice slicker, and can help cut down on the oxygen that mixes into the top layer of ice.

The last thing to control is the temperature of the ice itself. Technicians control the temperature to the hundredth of a degree. In the ceiling, are special infrared thermometers that can scan the surface of the ice for temperature differences. Then they change the temperature of the concrete slab so that the temperature is perfect.

The reason why the temperature of the ice is so important is that it controls the hardness of the ice. Cold ice has good glide characteristics, but it is hard to get a grip. Warm ice is softer -- it has good grip but bad glide. You would want pure glide except for two things -- getting started and taking a turn. For short races where the start is important, the ice will be softer to give it more grip. For the long races, the ice is harder for more glide. But it cannot be so hard that the skaters slip in the curves.

Image courtesy © 2005 Torino 2006/LaPresse.

A short race is only 500 meters long. The whole race lasts less than 45 seconds. Whether you win or not depends on how quickly you accelerate at the start and push during the race. For a short race, the ice needs to have some grip. The longest races are 10,000 meters, or six miles long. The acceleration at the start is a lot less important. You want glide so that the racers lose as little speed as possible to friction.

The ice for figure skating and hockey is a little thicker to keep from cutting all the way through to the concrete. It's about 1 inch thick rather than ¾ inches thick. They don't want to make it too thick though, or it is hard to keep the same temperature throughout the ice. Figure skaters prefer an ice temperature of 26 to 28 F. Ice in that temperature range is softer, so it grips the skate edges better. It is also less likely to shatter under the impact of jumps. Hockey players, though, prefer colder, harder ice. With many skaters on the ice simultaneously, it's easy for the ice surface to be chewed up at the temperatures preferred by figure skaters. For hockey games, the top of the ice is usually kept at 24 to 26 F.

Blade Runner Speed skating has been revolutionized by the clapper skate in the last two Winter Olympics, and many records have been broken using this new technology. The idea is very simple. The blade of the skate is hinged at the toe, and has a spring at the heel. As the athlete finishes a pushing stroke, his/her heel comes up off the ice first. The entire blade, however, grips the ice and the stroke continues until the toes leave the ice. Then the spring snaps the blade back onto the bottom of the boot for the next stroke.