This doesn’t speak to long-term Stuff Hits Fan. But if anyone is using the air-activated hand/feet warmers…you can save their hours of use. Say you have a packet that will keep heating for 7 hrs. You go out and do chores and are back inside within 2 hrs. You can save the other 5 hours of use by sealing the packs in a small airtight container. We just use small Ziplock bags..which are not that air-tight but ok for this. The pack will continue to use up the air in the container….and then shut down the chemical reaction.
Next day you open them up to air again…and stuff them into your gloves. Repeat until they have used up the chemical causing the heat reaction with air.
OldMtWoman