YouTuber SolarColorDust likes to coat things in thermochromic dust (the kind in mood rings and some thermometers). Here's a stormtrooper helmet.
Just pretend the vertical video got that way from the Death Star's trash compactor.
The mixture of automotive clear coat and thermal dust changes color at 86F and warmer. They also coated some shoes for fun:
• Thermochromic Color changing Stormtrooper Helmets using Thermal Dust! (YouTube / SolarColorDust)