Temperature plays a huge role in our lives. We make decisions large and small based on how hot or cold it is. Temperature influences the clothes we wear and how we drink our coffee or tea. We ask our smart devices to update us about the high and low weather forecasts for the day and then adjust the settings on our furnaces and air conditioners to our liking.

In those cases, temperature affects our personal comfort. It can also impact our health and safety — even the quality and performance of the products upon which we rely. It definitely changes the games we enjoy; ice hockey is one example.

The vulcanized rubber puck that hockey players slap with their sticks is supposed to travel smoothly across the ice floor of the rinks on which National Hockey League (NHL) games are held. However, when the temperature climbs above freezing, the puck can bounce and fly in unpredictable ways.

NHL referees keep pucks frozen at 15 °F in an insulated container off the ice. But during game action, the pucks warm up from friction and when referees pick them up and hold them in their hands. Until 2019, the game officials didn’t know when the temperature of a puck exceeded 32 °F; referees were just supposed to exchange them for a frozen one during time-outs and at other regular intervals. That didn’t always happen, so the NHL asked its paint partner, PPG, for a solution.

And that’s where a cold beer enters our story.

How You Know It’s Really a Cold One

Beer drinkers will tell you how big a role a cold one plays in their lives.

For example, the ideal temperature for Coors beer is 43 °F. But until Coors introduced beer cans and bottle labels that change color to visually indicate whether the contents are above or below that temperature, there was no way to know for certain. Coors solved that for beer drinkers everywhere by printing its logo on glass bottle labels with a thermochromic ink. The ink reacts to the temperature of the beer, turning the mountains in the Coors logo from white to blue at the ideal 43 °F temperature.

That thermochromic technology comes from SpotSee, a global leader in condition indicators and monitoring solutions. SpotSee monitors and indicators are designed to spot changes in environmental conditions, so users can identify any damage that had occurred throughout the supply chain. Even the smallest changes in temperature in addition to shock, tilt, location, humidity, and light sensitivity can make big differences in the quality of valuable products.

By tracking these small details, this technology helps users ensure that whatever is being transported – from lifesaving medicine and therapeutics to sensitive cargo – arrives safely and in the best possible condition.

I’m not suggesting that the temperature of beer is as vital to know as what’s happened to medicine or critical aerospace or automotive components. However, the popularity of the color-changing Coors logo was remembered by leaders at PPG as they evaluated options to eliminate the bounce in hockey pucks for the NHL. That led the PPG team to ask SpotSee to help them develop a paint for the NHL logo that changes color when it’s time to replace a puck during a hockey game.

Enhancing the Integrity of the Game

And that’s what we did. SpotSee and PPG tested thermochromic paint formulations on pucks in collaboration with the NHL’s team in Pittsburgh, the Penguins. We examined whether the paint altered how the pucks reacted when sliding on the ice and when they hit the metal goal poles or the boards and glass surrounding the rink.

The NHL then experimented with the pucks during its All-Star game and outdoor winter events and discovered how reliably they worked; today, the pucks feature the professional hockey league’s logo that transitions from purple to white when they’re too warm. They are used in all 2,624 regular-season games plus the Stanley Cup playoffs.

Thermochromic technology enables the NHL to enhance the integrity of the game by providing more consistent performance of the puck and a reliable way for referees to know when to replace a puck throughout the game.

What We Don’t See Protecting Us

Thermochromic technology is also deployed in ways most of us will never see but upon which we all rely. Examples include:

Automotive 

Original equipment manufacturers (OEMs) paint pick-up truck frames with it as a process validation indicator that the aluminum was annealed properly. Aluminum frames must be heated to a specified temperature to form the component while maintaining its material strength. The safety of the truck driver, passengers, and other motorists depends on it.

Medical 

Device manufacturers incorporate thermochromic pigments into one-time-use medical products whose quality can be compromised if temperatures during shipment and distribution exceed the intended range. We developed an ink that is irreversible; it changes color and stays that way to indicate at the package level when a temperature excursion has occurred to a device for heart catheterization procedures.

Another product, a blood bag indicator, offers the time and temperature histories of a blood unit. After a bag has been removed from a blood bank, the blood must be transfused into a patient within 30 minutes while maintaining a temperature between 1 °C and 9 °C. The irreversible portion of an indicator on the bag will change color from blue to a non-blue color as the blood temperature increases beyond 9 °C. Once the indicator has lost its blue color, it will not return to its original color, even if the blood unit is re-cooled. This ensures the user of the unit’s time and temperature histories.

Mining

The supplier of an inflatable ceiling deployed in underground mines incorporates thermochromic ink to change color when the ceiling material has been warmed but is still safe to use. The ink can revert to its original color when the temperature drops below a setpoint. However, if the temperature reaches dangerous levels, the ink turns irreversibly red to warn miners not to use the inflatable ceiling.

The Benefit of Knowing with Certainty

Temperature matters because it can change the quality, effectiveness, and safety of the products and devices we count on to lead our lives.

Everything from hockey pucks, beer cans, and truck components to life-saving mining equipment, medical devices, and medicines are designed to perform optimally at precise temperatures. Excursions above or below these setpoints can influence the outcome of a game or lead to devastating results if equipment or medical treatments are ineffective or fail.

Knowing what happened to products during transportation and distribution with certainty is the benefit thermochromic dye, ink, and coatings provide.