Winter Classic pucks to feature thermochromic coatings. The NHL has teamed up with PPG to create the official game puck for the 2019 NHL Winter Classic. The special coating will change from purple to clear when a puck's temperature is above freezing, providing a visual indication to officials that the puck should be replaced.
"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."