We've likely all seen it happen on TV and in film, and perhaps even in person. 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, which is why something like a metal wrench kept at 4°C feels much colder to your skin than air at 4°C.
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 kitchen – or aluminium – foil is a common household item and is often used in ovens. 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 cold metal? When the tongue makes contact, 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 things metal are made up of aluminium or steel (an iron alloy with carbon), making them fine heat conductors. They absorb 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 metal 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 metal, warming your tongue, the pole, and melting the ice.
Of course, this is difficult to do without help when you're stuck in place. 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 for help. Can't talk? Either text emergency services, or message someone you know, so they can phone for you. Vital PSA stuff this.
- 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.