It is a fact that warmer water CAN freeze faster than an identical container with an equal volume of cooler water, under certain conditions. It isn't a given that it will always happen. Moreover, the effect is subtle at best, and so the hot water would only freeze slightly faster, if at all.
It's a curious effect and one we physicists like to play with ideas for, but it's not huge enough to be of any practical consideration in normal day-to-day life, even if that day-to-day life happens to include camping in sub-freezing temperatures.
More importantly, however, for water to freeze, it has to be in contact with a temperature bath which is itself below freezing. And, since the water bottle would be placed INSIDE your sleeping bag, that would mean, for your bottle of hot water to freeze, the inside of your sleeping bag would have to be below freezing. In that case, I would say a frozen water bottle is the least of your concerns.
The effect is very subtle and depends very much on experimental conditions, and indeed on your definition of "frozen". For example, in an open container, the colder water is likely to form a "crust" of ice on the surface of the water, which will then act as an insulator, preventing convection, and slowing down the freezing of the rest of the water, while the warm water can tend to freeze from the bottom up, allowing the open surface of the water to lose heat, leading to the entire container freezing slightly faster than the initially colder one. So, if you define "frozen" as the first formation of ice, the cold one froze first, whereas if you define "frozen" as frozen solid, then the warmer one froze first. Or, if the conditions are slightly different, then all that crap I just typed out doesn't happen and it's entirely different.
In other words, it's a sort of silly little effect that's fun to point out as an example of how accepted ideas can often be false, but in reality it's so subtle and dependent on minute details that it's of very little importance in any grand scheme.
Old news, maybe ... I found on You Tube a short film on a plastic coke bottle filled to the top (with no air in the bottle) with water, then put directly into a fire. It didn't melt because of the bottle didn't have any air in it. It was a great way to make hot tea or a warm hammock. Anyone use this method?
We talked about it this weekend. We put a gallon just right on the coals and it held up fine, but we took it off before it boiled.
Aside from the melting, you have to make sure there's no air in the top b/c air expands when it gets hot...and can cause the bottle to explode. We just loosened the cap since we were just trying to melt the ice inside the bottle.
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IMPOSSIBLE JUST TAKES LONGER
I've used this method to stay warm in a house that did not have heat. I was in my 20 degree bag and put this in with me with just a t-shirt and boxers and I was roasting. This has become one of my favorite things to do on a cold night!
I put about 25 oz of near boiling water in a Nalgene covered in a wool sock under my TQ at the Mt Rogers hang. (10*F, 30*F down bag used as a TQ)
Approx. 30 minutes later, as I got inot my hammock, I noticed condensation on my GG CCF pad. At first, I thought the bottle was leaking, but as I investigated, the bottle hadn't leaked.
I dried off the pad and went to bed. Over the course of the night, I developed more condensation on the ccf pad (not enough to get up but enough to notice)
Anyone had similar expirences? Any ideas?
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I have a winter campout this weekend and have been thinking of this idea. I was wondering if I could use this hot water bottle idea at night while I was sleeping but put a hot bottle in each boot. That way when I wake up in the morning the boots wont be cold and stiff. Anyone see a problem with this?
I believe for some folks that is SOP.
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I do not see a problem with it, other than you boots may not provide the same insulation as a bag might. The bottles may cool much faster in the boot than in a quilt or bag. Try it out anyway, what do you have to lose? If you don't try it, your boots will still be cold in the morning
Last edited by Preacha Man; 02-17-2009 at 15:23.
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