Microwave Label
A reversible thermochromic ink printed onto packaging/label to show that a required temperature has been reached, or to warn that cooking has made food or liquid very hot. i.e. Hungry Jacks Maple Syrup label changes colour to show that it is warm enough to pour.
Thermochomric ink printed on lid
Interactive heat cards
Reach the right temperature to see it change
Warm up and see if your a winner