DIY cold packs that recharge <65F

This dude is experimenting with some neat stuff here. He created a stable, non-toxic PCM that can be recharged with the cold of a basement (or a hole in the ground!) using inexpensive ingredients (food-grade sodium sulfate, table salt, water, and xanthan gum) that reheats more slowly than ice.

He shows how to make little packs you can use in a cold vest and larger, torso-sized packs that could help a person with heatstroke using a towel soaked in the PCM and contained in a trash bag.

I think this is pretty exciting and could be a great project for mutual aid groups - would be awesome to have some of these cold packs to give out with a FNB meal.