Thermochromic Dinosaur Mug

Good point. When I saw the 'hot spots' linger, I did worry that I might have burned the pigment with the laser. But no, the pigment is just fine. Still works as new as far as I can tell. I can't explain how it is possible for some spots to apparently stay hotter than their surroundings for a while. I guess the temperature difference is only a fraction of a degree. The tricky part in this trick is not getting a 980 nm laser and pointing it at the mug. The tricky parts is getting the temperature just right. It has to be very near the transition temperature (and have the laser focused to be intense enough to heat up the pigment fast but not burn anything). Maybe the hot spots are a little thicker/thinner, have different pigment densities or other imperfections and/or some humidity was absorbed in some of the pigment from being rubbed in cold water. But then again, wouldn't most of those be noticeable in the hot/cold water tests too? I really have no clue. Even in simple-looking experiments, there are always tons of factors to account for... For info, the laser experiment was performed with hot but far from boiling water still in the cup. I tried several tests without water in the mug (but with the mug still hot). Never got that too work. Maybe coincidental or maybe the water's heat capacity behind the pigment is necessary for this to work. May have to examine this is in more detail - but I'm not even sure I can replicate the effect again. May have been pure luck with all the factors adding up just right :D

I would have guessed IR laser too. But it looks like some spots linger for a bit longer than they should if they are just heating the top layer briefly, The spots also seem to have far too clearly defined borders, did the laser ruin the colour changing pigment on the spots that seem to stay transparent?

Bingo! Though it takes more than just pointing the infrared pointer at the mug ;)

I see you're using your 980nm laser at the end :)

iamdarkyoshi