Choosing the Right Color-Change Temperature for Thermochromic Inks
Updated: Jan 14, 2020
Coors Light. Coca-Cola. Mountain Dew. Johnny Walker.
Many brands have successfully incorporated thermochromic inks into their beverage containers and secondary packages to underscore the importance of drinking their product at cold temperatures, engage consumers and build lasting brand loyalty in innovative ways.
Consider this scenario: You sell a well-known beverage internationally that needs to be fairly cold for best taste. Your executive team decides that adding a permanent Aqua-colored themochromic ink to your brand will educate customers, boost their brand experience and lift sales.
You know that the beverage should be no warmer than 50°F / 10°C for the best consumer experience, but the marketing team wants to play it safe and have the color change at 32°F / 0°C because the colder the better.
Ready to design, trial and commercialize with the converter, right?
Not so fast.
There’s a lot to think about when selecting the best target temperature for a thermochromic package feature. Here are a few considerations:
Container material. The thermodynamic properties of aluminum, glass and plastic require different approaches. Aluminum, as you would imagine, conducts heat very well, so it will warm more quickly than glass, which naturally insulates. On a PET bottle, the printing typically isn’t on the bottle itself but rather on a label that’s affixed to the bottle and may or may not be touching the bottle surface.
Target market. Did you know that a 2015 survey* revealed that the mean refrigerator temperature in England was 6.2°C / 43.2° F? In the U.S., the FDA recommends keeping refrigerators lower than 4.4°C / 40°F. Setting them too much lower risks freezing sensitive foods like milk, fruits and vegetables. The point: Make sure that you’re not asking customers to change their behavior or appliances to enjoy your product.
Thermochromic ink characteristics. Standard cold-activated and heat-activated inks have what’s called a color development window – the temperature difference between the color-off state and the color-on state. In the case of the mountains that turn blue on the Coors Light can, the color development window is between 12°C and 8°C, which means that color starts appearing at four degrees above the target full-color temperature. It’s possible to narrow or widen the color development window, depending on the application.
Colder, faster. The laws of thermodynamics haven’t changed: When an object that’s very cold moves into a relatively warm environment, it won’t stay very cold long. From a customer experience standpoint, if you want customers to see your thermochromic ink feature on a beverage chilled to near freezing, they won’t see it long. Once the beverage is taken from the freezer, it will lose color because of warming fairly quickly.
The experts at CTI talk with brands and converters every day about the best customer experience, best target temperature, color development windows, qualifying inks and implementing successful thermochromic features on CPG, industrial and medical packaging.
Contact our team today to discuss your project.
* Evans EW, Redmond EC. 2015. Analysis of older adults’ domestic kitchen storage practices in the United Kingdom: identification of risk factors associated with listeriosis. J Food Prot 78:738–45.
Interested in how to bring packaging innovations to your brands and customers?
Contact CTI today for samples and information on how you can use this technology on your existing cans, documents, labels or closures.