Hockey rink ice is more than just frozen water: it takes a specific temperature and chemistry to get it just right.
Slow Ice, Fast Ice
Everybody knows that hockey is played on ice and ice is frozen water. But did you know that not all ice is the same? It turns out that the temperature and chemistry of the ice makes a big difference.
Hockey players prefer what is known as “fast ice” which is harder and colder with a smooth, slippery surface. “Slow ice” is softer and may have a rough surface. While hockey players want to move fast, figure skaters often prefer the slower ice, which holds up better for jumps and landings. Then there's what's in the ice.
What's in the Water?
Water purity plays a big part in making the perfect ice for hockey. Ice made with water that contains dissolved alkaline salts may have a sticky feel to it. Those salts will also dull the blades of skates. That’s why many ice rinks now use water purifiers to filter the water that is used for the ice.
The technology used in indoor ice rinks is the same type found in refrigerators and air conditioners. Brinewater is pumped through a system of pipes under the ice. Those pipes are built into the concrete that makes the arena floor. And because brinewater freezes at a lower temperature than just water, that allows the water to stay a liquid as it moves through the pipes but still be cold enough to freeze the water poured onto the concrete floor.
The ice is built in layers. Those layers vary between 1/30 and 1/16 of an inch thick. The first layer is sprayed directly onto the concrete floor, measuring about 1/32 of an inch thick. It freezes almost immediately when it hits the cold floor.
Then, more super-thin layers are applied. They are painted white to contrast with the black puck, and lines and logos are also painted on. The entire process can take almost 48 hours. The ice is only about one inch thick when everything is finished.
In addition, the official size of a National Hockey League rink is 200 feet long and 85 feet wide. To make the an ice sheet with this large of a surface area requires about 10,600 gallons of water.
In PNC arena in Raleigh, like in most hockey arenas, the ice stays in place for the entire hockey season. There is a special flooring laid on top of the ice to allow for NC State basketball games and other events to be held in the arena.
The Zamboni's role
It’s the job of the ice technician to care for the ice surface using a Zamboni once the ice sheet is built. The Zamboni scrapes the ice surface and collects the snow. The machine also puts down a thin layer of heated water. The water is warmed to about 140-145 degrees. It doesn’t melt the ice because it freezes pretty quickly. But the hotter the water the smoother the surface it creates.
Who's ready to lace up those skates and hit the one-inch-thick, painted, carefully cultivated ice?
Frank Graff is a producer/reporter with UNC-TV, focusing on Sci Tech Now North Carolina, a weekly science series that airs Tuesdays on UNC-TV. In addition to producing these special segments, Frank will provide additional information related to his stories through this North Carolina Science Now Reporter's Blog!