Frozen pucks are the best pucks.

The National Hockey League has taken steps to ensure that the 2019 Stanley Cup Playoffs are played only with frozen pucks.

For this year’s postseason, the league is using thermochromic pucks that change color based on temperature.  The NHL first tested these at the 2019 Winter Classic between the Boston Bruins and Chicago Blackhawks at Notre Dame Stadium.  Now – after being given the green light for expanded use – they’re back for the playoffs.

Linesmen can check the puck color before each faceoff to ensure only frozen pucks are in play.  Frozen pucks have the playoff logo in purple. As they heat up, the logo will turn white.

“Hockey pucks are made of vulcanized rubber and glide smoother and faster when frozen,” said Dan Craig, NHL Vice President of Facilities Operations. “Freezing a puck eliminates bouncing, and game officials closely monitor the puck for temperature changes that affect performance while in play. A coating that changes color when the puck is above freezing will more accurately alert the officials that it is time for a replacement.”

Pucks are typically stored at around 14 degrees Fahrenheit in a small freezer within the penalty box area, with an average of 15-20 used in a game.

Here’s a look at the puck freezer from Ron & Don: