These may look like the medical plasma bags you’d find in a hospital but they’re not. They are something so much cooler. Literally.
Dr Cool and Dr Hot are actually thermal packs designed to help you recover from your aches and pains from a hard days work or a long night out.
Dr Cool can be kept in the freezer for when you need it. The cooling gel stays cold for a real long time giving you a constant supply of cool to keep on your sore muscles. Dr Hot on the other hand can heat up with the press of a button found inside the bag. Don’t ask me how that works, I believe it’s some sort of voodoo magic. To recharge the bag, simply boil in water for 10 minutes after use and it’s ready to go again.
Okay, it’s not really magic. I did some reasearch and here’s how Dr Hot Bags work:
Each pack contains sodium acetate and water. Sodium acetate is very good at supercooling. It “freezes” at 130 degrees F or 54 degrees C, but it is happy to exist as a liquid at a much lower temperature and is extremely stable. Clicking the disk, has the ability to force a few molecules to flip to the solid state, and the rest of the liquid then rushes to solidify as well. The temperature of the solidifying liquid jumps up to 130 degrees F or 54 degrees C in the process.
When you boil the solid you melt it back to the liquid state. You have to completely melt every crystal or the liquid will quickly re-solidify. You can repeat this cycle thousands of times, just as you can freeze and melt water as many times as you like.
Now that IS amazing. Science!