I did a short overnight trip this weekend, and it got fairly cold for the area–low of around 7 *F (not including windchill which was -1).
I filled up a large Hydroflask vacuum insulated thermos with near boiling tea, with a down sleeve over the top, and left it in my car.
When i got back to my car early afternoon the next day, and tried to open the Hydroflask bottle–i found a curious thing, as i unscrewed it and tried to pull off the lid, i couldn’t, and it would suck back down. Â After trying this a few times, i gave up as the suction was too strong for me.
I’m guessing what happened is that hot, expanded air, cooled and contracted enough, to create a strong vacuum effect like in canning.
Never had this happen before. Â Would screwing it less tightly help to prevent this?
