The Reason Hockey Pucks Are Frozen in the NHL

September 13, 2021

Photo of a hockey puck on the ice.

A National Hockey League game can be an exciting event, but something is done to the hockey pucks that keep the games from becoming a little too exciting.

A hockey puck is made of vulcanized rubber, and rubber, as you know, is bouncy, especially at room temperature or warm. That is why the NHL uses frozen hockey pucks for all its games, so the pucks aren’t too bouncy. The pucks (or biscuits as they are sometimes known) are kept in a freezer in the penalty box at a temperature between 14 degrees Fahrenheit and 20 degrees Fahrenheit (-10 and -6.7 degrees Celsius) to ensure they are frozen before they are put into play.

NHL rules state that the home team will be responsible for keeping game pucks frozen, and they should be kept in the penalty box under the watchful eye of an official or other attendant. A home team does this by transporting fifteen pucks from their freezer to the penalty box cooler. They are even transported in a cooler. At the beginning of the second and third period of the game, fifteen more pucks are transported from the home team’s freezer to the penalty box cooler.

Things get even more specific when a puck is in play. After a puck has been used for more than two minutes, it gets replaced with a new frozen puck so that consistency is guaranteed no matter which point a player gets in the game. It’s up to a linesman (a referee official) to make the exchange from a used puck to a new frozen puck, and they usually do that before the next face-off.

If a used puck is returned to the penalty box freezer attendant, it is not used again and is returned to the home team’s freezer after the period ends. Pucks are also exchanged during commercial time-outs in the same way. About 25–30 pucks are used on average in a typical NHL game. Look for the exchange the next time you happen to watch a hockey game.

Bonus Fact About Hockey Pucks:

There was one time when a different sort of hockey puck was used in NHL games. It was called the FoxTrax puck, and it was first used during the 1995–1996 NHL season. The Fox Network developed the puck, and it was supposed to make viewing the puck’s movement easier. It was composed of a battery and a small computer at its center, along with infrared emitters that pulsed. These pulses were then picked up by sensors around the rink.

The movement was processed by a computer that put a blue halo around the puck. When the puck speed went above 50 mph, it had a red trail. When it went over 75 mph, it changed to green. The FoxTrax pucks only lasted about 10 minutes on battery power, and each one cost around $400. The glowing puck experiment ended when the Fox Network didn’t renew their NHL contract after the 1998–99 NHL season.

Sources: NHL Officials, SB Nation, Hockey World, Made How

About the author 

Daniel Ganninger - The writer, editor, and chief lackey of Knowledge Stew, the author of the Knowledge Stew line of trivia books, and editor of Fact World and the Knowledge Stew sister site on Medium, our ad-free subscription sites. I hope you learn many new things here that add to your knowledge.

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