ColdMark ThermoLabels are used to protect products that are sensitive to extremely cold temperatures. These stick-on labels can be applied to a product, package, carton or master pack. Each has a tiny tube with a colorless bulb. When exposed at or below its response temperature within 60 minutes, it will turn cloudy with streaks of violet.

Once warmed up above the response temperature again, the bulb changes irreversibly to a uniform violet color. ColdMark is a tamperproof method of verifying when freeze damage has occurred during shipping, storage or handling of TATS products such as vaccines, providing a permanent record for quality assurance purposes.