Drew writes “I used some discarded beverage bottles, aluminum foil, duct tape, and expanding insulating foam to make a thermal carafe for next to nothing. Then I tested it against a real Thermos and an uninsulated bottle to see how it compared. Conclusion: a thermos made from junk isn’t quite as good as a store-bought one, but it’s much cheaper and a lot more fun.” – Link.
8 thoughts on “HOW TO – Make a Thermal Carafe”
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Hot liquids will cause chemicals to leech out of the plastic containers. Only do this with glass/metal bottles.
These plastic bottles will eventually harden with age and begin to release toxins. I would strongly advise against doing this.
Will glass/metal bottles work as well in terms of keeping the heat in?
Hi, I’m the Maker of this project.
I’ve received several emails about this project, and I will be creating an additional web page to cover the feedback I have received. (Look for it tomorrow!)
However, since some of the feedback has been about the use of plastic bottles, I’ll jump in and post in the context of this thread as well.
I’m not a chemist or a materials scientist, but it seems to me like the plastic is pretty inert, even at relatively high temperatures. (We’re talking about 200 degress F, not frying pan hot.)
I did some googling, and I did not find anything that addresses the specific issues raised here. However, I did find the following links that suggest reusing plastic bottles and heating them is relatively safe.
http://debris.com/journal/832
http://www.plasticsmythbuster.org/
http://www.snopes.com/medical/toxins/petbottles.asp
http://www.snopes.com/medical/toxins/cookplastic.asp
In any case, it is only the inner bottle that comes in contact with the beverage, so you could substitute a glass bottle pretty easily if you have a concern about using plastic. It might be harder to find a metal bottle.
My assumption is that either glass or metal will have a greater mass than the thin plastic bottle and soak up more heat when a hot beverage is poured into it. It should keep the heat in just as well as plastic, but the initial temperature drop might be greater. To counteract this, the thermos could be pre-heated with hot tap water.
A metal bottle might conduct heat away from the beverage faster than plastic, but it would be more shatter-resistant than glass.
Like I said, all this info will be added to my project page soon, but I wanted to post it here in context. Thanks for your feedback, everyone!