I’m completely obsessed with thermochromatic ink.  I’m obsessed with ink in general, ever since my undergraduate days in the print shop in Walsh.  But I am especially obsessed with thermochromatic ink – and not just because it’s how I know whether my beer is cold enough.  Thermochromatic ink changes color when the temperature drops above or below a specific threshold.  I found this lovely and slightly dense explanation of how this happens while I was looking at Chromazone Thermostar Ink the other day:
“ChromaZone is a microencapsulated thermochromic pigment which changes from colour to colourless …