From 50 Dangerous Things: boil water in a paper cup

50Dt-Boilwaterinapapercup-1 A few days ago I wrote about Gever Tulley and Julie Spiegler's kids' activity book called Fifty Dangerous Things (You Should Let Your Children Do). Gever and Julie kindly gave me permission to post another activity from the book: boiling water in a paper cup. Click the thumbnail for the full size image.

Fifty Dangerous Things (You Should Let Your Children Do)


  1. I’ve done this over a campfire. It’s interesting to see the top part of the cup catch fire and burn away, leaving the surface of the water right at the rim of the cup.

  2. I did this in Scouts way back when. We hardboiled an egg on a fire in a paper cup. I had completely forgotten about that.

  3. I remember, as a kid, having a book called “Boiling water in a paper cup…” or something like that.

  4. Awesome idea. I discovered this basic principle when I was one day inspired to hold a lighter up to a plastic bottle of water. I look forward to convincing some friends to bet me this won’t work and then triumphantly prove them wrong.

    Also the phrase in my captcha is “bedded that” as in “yeah, I bedded that.”. Raunchy.

  5. I read long ago about a “roughing it” version of this that used large green leaves folded into a cup.

  6. Is there by any chance a version with metric (SI) units?

    From Wikipedia:

    Only in the United States and a few other countries (such as Belize) does the Fahrenheit system continue to be used, and only for non-scientific use

    1. Incredibly, it turns out that this trick still works if you tell the cup you’re using Fahrenheit. I don’t know how, but it’s true! Admittedly, the water still needs to be in Celsius though.

  7. Amazon has this book for about $25. Just picked up a copy, hope the rest of the experiments are as interesting…

  8. a variation of this idea is to use an origami paper kettle (easy to make); then you get a jet of steam from the top. (Warning: do not let the “wings” catch fire !)

  9. @Ospin: Really? There aren’t that many numbers with units to convert, and it is straightforward. But here you go:

    At 1000 m water will start to boil at 97°C – a full 3 C° lower than at sea level… Water boils at 100°C (or less) but paper doesn’t burn until it gets to almost 260°C.

    We Americans may not be very good at learning other languages, but many of us are fluent in multiple systems of units (and yes, my distinction between °C and C° is an intentional nitpick: the former is a temperature, the latter a temperature difference).

    1. @Haakon IV:
      Possibly, Ospin was making some comment that the original, nice, round 1000m was converted into feet for Americans (3300ft), but the original number was lost.

  10. So if I could get my wife to make meatloaf in the form of a cup and fill it with water, I could for once in my miserable life have an unburned dinner??

    Handy info!!

  11. This reminds me of the time I filled a styrofoam cup with water and, using a can of hairspray and a lighter as a flame-thrower, tried to burn up the cup. The cup melted until only a super-thin layer remained, without a single leak. I guess the water kept the rest from burning up. The cup was too thin to pick up without spilling the water though.

  12. An interesting (and sad) real world analog for this experiment: when I came back to New Orleans after Katrina and went exploring in my neighborhood, I found a house that caught fire during the storm and had burned down… but only to the waterline – anything on the ground floor that was underwater remained intact. (photo from my flickr set:

  13. Same thing works quite well with plastic baggies, just the normal sandwich baggies. We used to reheat coffee this way in jail.

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