In that famous scene in the movie Christmas Story, a kid "triple dog dares" another kid in the schoolyard to put his tongue on a metal flag pole to see if it will stick. Lo and behold, it sticks. The bell rings and all the kids go inside, save for the one kid whose tongue is stuck to the flagpole. Eventually, the firefighters come and pull him off, but not without a big struggle and much pain. While this is a fictional movie, there is much truth to this scene. Yes, a tongue, under the right circumstances, can get very much stuck to metal. Why does this happen? What are the right circumstances? Why does it stick metal and not plastic, wood or rubber?
First off, as you may have noticed, your tongue is coated with saliva (shocker), which is about 99.5 per cent water. In order for the tongue to not freeze when sufficiently cold, the body sends blood rushing to the tongue to heat it up.
However, metal, in nearly all of its forms, is a great conductor of heat, meaning that heat freely flows (transfers) through it. If something conducts heat well, (most of the time) you can feel it — literally, which is why something like a metal wrench kept at 25 degrees Fahrenheit feels much colder to your skin than air at 25 degrees Fahrenheit. Of the common metals, copper and aluminium are best at this. Some of the most expensive cookware is made out of copper due to its characteristic as a thermal conductor. As for aluminium, there is a reason tin — or aluminium — foil is a common household item and is often used in ovens. (And if you're curious: Why is Aluminium Foil Shiny on One Side But Not the Other?) While iron conducts heat at about a third of the rate as aluminium, it still does it quite well. Stainless steel conducts heat at about a fifth of the rate as iron but is also often used as kitchenware, as it's still relatively great at conducting heat.
On the other hand, wood, plastic, and rubber are not good heat conductors, with wood being 150 times less conductive than stainless steel. That is why when you stir a boiling pot with a wooden spoon, you can hardly feel the heat in the handle. With a solid steel, aluminium, iron, or copper spoon, if you continued stirring like you would with the wood spoon, you would quickly find yourself with a nice burn for your efforts.
So, what really happens when you put your warm tongue on a cold flagpole? When the tongue makes contact with the pole, the heat is rapidly transferred, cooling the tongue and forcing the body to send warmth in the form of blood and heat energy. The problem is that, today, most metal flag poles are made up of aluminium or steel (an iron alloy with carbon), making them fine heat conductors. The pole absorbs the heat quite readily, literally sucking the warmth from your tongue faster than your body can supply it. The saliva on your tongue then freezes (provided it is below freezing), with the resulting ice latching onto the flagpole and your very porous tongue. You are stuck. Materials that are less ideal conductors of heat won't provide this same rapid effect, nor even in many cases are they capable of cooling the surface of your tongue faster than your body can heat it to keep it above freezing. In some cases, the material might even have an insulating effect.
The more important question is, if found in this situation, how do you get unstuck? First off, do not pull or tug. If it is really cold and really stuck, there is a risk that a piece of tongue will come right off, causing much pain and blood. Thankfully, there is a simple solution- pour warm water over where the tongue meets the pole, warming your tongue, the pole, and melting the ice. Of course, this is difficult to do without help when you're stuck to a pole. If by yourself, try breathing hot breathes onto the area. The moisture and warm air should dislodge the tongue. One could also try using warm hands and fingers to melt the ice. If none of these things work, call the local fire station. If you find it difficult to communicate your problem with your tongue stuck, today many emergency call centres accept texts. (See: How Did "911" Become the Emergency Call Number in America?)
- Some of the best solid heat conductors are actually diamonds. According to Livescience, diamonds can be up to five times better thermal conductors than copper. The strength of its covalent bonds creates this characteristic, along with the strength in general of a diamond (long considered one of the most unbreakable items in the world, though in truth they are often easily crushed to dust with a simple blow from a hammer). Despite this and counter-intuitively, even if the stone is conducting heat, it is generally cool to the touch.
- Licking an icicle can also cause a stuck tongue. While not as a good of a heat conductor as aluminium or iron, it is about ten times better than rubber at this. As a rule, just stopping licking icy things outdoors.
Matt Blitz writes for the wildly popular interesting fact website TodayIFoundOut.com. To subscribe to Today I Found Out's "Daily Knowledge" newsletter, click here or like them on Facebook here. You can also check 'em out on YouTube here.