WEBVTT - Why Is It Painful To Bite Aluminum Foil?

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<v Speaker 1>Welcome to brain stuff from how stuff works. Hey, everybody,

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<v Speaker 1>it's me Christian Sager. Now today's question is why is

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<v Speaker 1>it so painful to bite into aluminum foil? And if

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<v Speaker 1>you're from across the pond, you may be wondering right now,

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<v Speaker 1>why is he saying aluminium instead of aluminium? Well, I'm American,

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<v Speaker 1>That's how I pronounced it all my life. I apologize.

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<v Speaker 1>We're gonna go forward with aluminum. But it's a good question, right.

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<v Speaker 1>So first things first, it's actually not painful for everybody

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<v Speaker 1>to bite into this foil. It's painful for people who

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<v Speaker 1>have fillings or crowns made of metal. You probably already

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<v Speaker 1>knew that part, So let's fast forward. What is actually

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<v Speaker 1>happening here. It's sort of like making a battery. So

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<v Speaker 1>how does this happen exactly? Well, first, it's two different metals,

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<v Speaker 1>the aluminum foil and the metal in your filling or crown.

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<v Speaker 1>They have what's called an electrochemical potential difference, and they

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<v Speaker 1>create the sort of voltage in the environment in your mouth,

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<v Speaker 1>which is moist and salty. It's produced by your saliva.

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<v Speaker 1>It's perfect for these two things to come into contact

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<v Speaker 1>this way and to transmit energy. The electrical stimulation from

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<v Speaker 1>this bootleg battery you have created is hitting the nerve

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<v Speaker 1>in your tooth, and that is producing that weird, unique pain.

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<v Speaker 1>The production of this current between the contact of two

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<v Speaker 1>dissimilar metals. It's actually a pretty old concept. It's called

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<v Speaker 1>the voltaic effect. It's named after a guy named Alessandro Volta,

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<v Speaker 1>who most people credit with discovering this. In fact, if

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<v Speaker 1>you want to learn more about this, on my other podcast,

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<v Speaker 1>Stuff to Blow Your Mind, we went really far into

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<v Speaker 1>voltaic batteries in an episode we did on Frankenstein. Now

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<v Speaker 1>Volta he was making extra batteries a long time ago,

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<v Speaker 1>and what he did was he stacked these dissimilar metals

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<v Speaker 1>together and in between them he would put water her

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<v Speaker 1>paper soaked with salt water. And he found that by

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<v Speaker 1>doing this he could create a very low power battery.

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<v Speaker 1>So that's essentially it. That's what's happening when you open

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<v Speaker 1>a candy bar and you bite down on a piece

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<v Speaker 1>of chocolate that still has a little bit of foil

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<v Speaker 1>in it and you freak out because it's painful. You're

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<v Speaker 1>essentially creating a battery in your mouth. Check out the

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<v Speaker 1>Brainstuff channel on YouTube, and for more on this and

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<v Speaker 1>thousands of other topics, visit how stuff works dot com.