Can You Boil Water in a Paper Cup?
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Can You Boil Water in a Paper Cup?

Is it true that you can actually boil water in a paper cup? Apparently so, if the cup contains a liquid which acts as a 'heat sink...'

Boiling Water in a Paper Coffee Cup? Is this Possible?

Until tried, one cannot know if something is possible. Not that anyone would want to boil water in a paper cup for any practical reason but yes, it is possible to do. To boil water in a paper cup over an open flame or upon an electric heating element is a good scientific experiment if nothing else.

A Mesolithic method of boiling water to cook food, or prepare hot water for ritual bathing involved rolling round hot rocks from the campfire into a sinkhole lined with animal hide and filled with water or snow. They would dig a shallow depression in the ground and lay the large animal hide across the hole fur-side down. This formed essentially a sink in the manner that we would recognize it. This sink would be filled with either water or snow in preparation.

With a roaring campfire and the hot fairly round rocks encircling it, they would roll several of these hot rocks into the watery depression. This caused the snow to melt or water to become hot in the other case. Using a forked branch, the rock would be removed and returned to the campfire. This method would be repeated causing the water to reach boiling temperature.

Chunks of meat and vegetables would be added to the 'soup pot' and introduction of more hot rocks would continue to rise the temperature of the water, cooking the soup. The animal hide will not burn, and can only rise to the temperature of the water that it contains, water which boils as only 2120 F. Even though the temperature of the hot rocks far exceeds the boiling point of the water, the animal hide will not actually burn until all the water has boiled away. A hide so used this way could be re-used for this procedure.

In science, this is called a 'heat sink.'

A Heat Sink Demonstration: How to Boil Water in a Paper Cup

This can be demonstrated using a common un-waxed paper cup. A double-insulated cup won't work, nor the stacking two cups one inside of the other. Just a plain ol' paper 'Dixie'-style paper cup will suffice.

flat bottom un-waxed paper cup, filled with water

(image source)

This can be performed over a flame, or even upon electric stove burners but the paper cup probably has a paper ridge around the bottom that should be trimmed off with scissors first. Be fair; the cup must lay flat upon the heat source and not have any ignition source 'wings' that can scorch and burn.

Now, fill the flat-bottomed un-waxed paper cup with water and place it upon the heating element or introduce the heat source if you are heating over a candle or open flame source like a Bunsen burner. Nothing happens. At least, that is what it appears. One might have guessed that the paper cup would have ignited immediately. -What is happening here?

The heat is being transferred through the bottom of the paper cup and into the water (the 'heat sink') where it is absorbed and distributed. Eventually, the water temperature rises to boiling and the cup continues to maintain its integrity. Within a minute or so, the water begins to boil. You are boiling water in a paper cup!

The paper cup has a flash-point of over twice the temperature of boiling water and thus, will not ignite until the 'heat sink' material (the water) has fully evaporated. Then and only then will the paper almost immediately burst into flame.

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Comments (8)

Hey that would a cool experiment :)

You're like a genius. However do you think of these things? lol

One learns something new every day great article Stickman

Cool. :)

Sounds improbable but I suppose it must be true!

microwave anyone?

Hot Paper Cups

This is an interesting post, but it should be noted that the regular style of disposable paper cups are not actually designed to hold boiling liquids. The glue which holds the base on is only designed to take hot liquids rather than boiling. I suppose your milage may depend on the quality of cup used, but there is always a chance of the glue melting and causing a spillage. Be careful!

Heather Ann Witt

Might try this next time I am camping!!1