My customer asked me: “What’s the deal with colour-changing ink?”

Attractive Coors Light Product Trainer: “This year we’re launching the Coors Light ‘Cold Certified’ bottle. When the mountains change colour, your beer is certified cold.”

Guy 2: “I don’t see mountains…”

Guy 1: “So when does the bottle change colour?”

Attractive Coors Light Product Trainer: “No, the label changes colour.”

Guy 2: “My beer has not changed colour.”

Guy 3: “When does the label turn into beer?”

Guy 2: “I still don’t see a mountain.”

Guy 1: “I like it.”

Attractive Coors Light Product Trainer: “No the label changes colour.”

All: “Ohhhhhhhhhhhhhh…”

Legendary Voice-Over Man: It’s the new Coors Light cold certified bottle. When the mountain changes colour, your beer is certified cold.”

The Coors Light Brewing Company has done a fantastic job promoting its cold certified beer. Commercials like the one mentioned have made printing with colour-changing ink memorable and marketable. So we’ve all seen and heard the Cold Certified “cool” factor, but how does it work? Also, what are other practical applications of this technology?

Thermochromism

Thermochromism is defined as the ability for a substance to change colour at a specific temperature and is achieved through the chemical composition of matter. Thermochromic ink was developed in the 1970s to temporarily change colour when the ink was exposed to heat. Liquid crystals (manufactured to react at specific temperatures) and leuco dyes (which have a response range that is less accurate than liquid crystals, however allow for a wider range of colours to be achieved) are microencapsulated in the thermochromic pigments to react to heat or cold. In the case of the Coors Light cold certified bottles, thermochromic ink that has been formulated to change colour when the label reaches four degrees Celsius.

Although the cold certified beer bottles are a neat marketing initiative, the practical application of this technology is often overshadowed by its gimmicky appeal. There are other, much more practical applications for colour-changing ink technology. Everything from microwavable packaging to interactive marketing campaigns to security features on cheques employ colour-changing ink in very useful ways.

Practical Applications

• Hot or cold packaged products
• Interactive marketing and printed promotional campaigns
• Everyday consumer products
• Security applications

Chromatic Technologies Inc. (CTI) is an ink manufacturer that specializes in special effect inks for lithography, gravure, flexography and screen printing processes. Its product lines range from thermochromic ink to photochromic ink (UV and sunlight sensitive) to glow in the dark to colour-shifting ink. With regards to thermochromic ink, CTI manufactures a high-temperature formulation that changes colour just below the pain threshold of human skin, so the consumer knows when the product they are about to eat or drink becomes the optimal temperature for consumption, thereby acting as a safety feature.

Other packaged products that also benefit from thermochromic ink include products that cannot be exposed to certain levels of heat or cold, including everything from medications to ice cream. When the label and, therefore, the product is exposed to temperatures outside of the range they are required to remain, the retailer or consumer will have a quick reference to know that the product should not be used.

Forehead thermometers, battery testers, graphic t-shirts that change when exposed to sunlight and mood rings are all everyday examples of thermochromic ink technology subtly at work. Security features for cheques, prescription pads, and other important secure documents are further practical examples of this technology. By employing this straightforward printing process that is not easy to replicate, extremely useful and functional products result.

A unique example of integrated product promotion and packaging comes in the form of a Pizza Hut delivery box. This packaging employs thermochromic ink to guarantee customers that their pizzas are hot and fresh when delivered (turning from black to red when the pizza box measures temperatures above 45 degrees Celsius). This is not only a practical application that is aimed at increasing customer preference, but it is achieved in a very economical way. There are no fancy thermometers that have to be used or expensive add-ons to the packaging (that may not only cost an exorbitant amount to produce, but there would also be the added cost of marrying them to the pizza boxes), this technology is simply printed on the box and, therefore, integrated into normal production. Interactive product marketing and promotional campaigns, such as this example, are very well suited to benefit from this interactive process.

There are endless possibilities for colour-changing ink applications and it’s just a matter of time before we see even more unique uses of this process. In the meantime, let’s celebrate this achievement in ink technology with a perfectly chilled, blue-mountain cold one. Cheers!