Well to answer the chewing aluminum foil question.
Biting on aluminum foil can be painful and is usually noticed if you have metal in your mouth from dental work (e.g. fillings, crowns). Basically, when you bite on foil, you set up a battery in your mouth and the electrical current stimulates nerve endings in your tooth. Here is what happens:
If you have no metal dental work in your mouth, you should not feel this effect
Biting on aluminum foil can be painful and is usually noticed if you have metal in your mouth from dental work (e.g. fillings, crowns). Basically, when you bite on foil, you set up a battery in your mouth and the electrical current stimulates nerve endings in your tooth. Here is what happens:
- pressure from biting brings two dissimilar metals (aluminum foil, mercury in fillings or gold in crowns) in contact in a moist, salty environment (saliva)
- the two metals have an electrochemical potential difference or voltage across them
- electrons flow from the foil into the tooth (i.e. electrical current)
- the current gets conducted into the tooth's root, usually by the filling or crown
- the current sets off a nerve impulse in the root's nerve
- the nerve impulse is sent to the brain
- the brain interprets the impulse as pain
If you have no metal dental work in your mouth, you should not feel this effect
Besides bash threads.
Why is aluminum foil not hot when it comes out of the oven?
Good observation, Zack, but you have reach the wrong conclusion about the
aluminum not initially being hot. Anything sitting in a hot oven tends to
reach the same temperature as the oven high. (see note at the bottom) So,
say your mother is warming up a loaf of bread (maybe with some butter
between the slices of bread) at 150 to 200 F. When the oven door opens,
that aluminum foil is at the 150 to 200 degrees as the oven. However,
notice that the aluminum foil is very thin. There is very little actual
aluminum and it is spread over a relatively large area (standard aluminum
foil is about 0.0007 inches thick; heavy duty foil is about twice as
thick). As a result cool air outside the oven cools the foil quickly. If
your mother grabs the foil with her fingers, she is relying on the cool
room air to cool the foil surface quickly to keep from burning herself.
Also her fingers themselves have a lot more mass than the aluminum foil
that they are in contact with so usually only the top surface of the skin
would be heated. Your mom's fingers might be a little toughened from all
of her work buttering that bread so she doesn't notice a slight bit of
damage to the surface layer of cells. Also, if her hands are damp, the
water on the surface of her hands will also cool the foil.
There isn't anything magic about the thin aluminum. If the bread were
wrapped in paper, you could also handle it directly from the oven. The
paper would, in fact, be less likely to burn your mom's fingers than the
aluminum, since it doesn't conduct heat nearly as well. (Unless of course
your oven temperature is set too high and the paper starts on fire - but
that is another story!)
The aluminum foil surrounding the bread is exactly the same material with
the same properties as the aluminum cookie sheet that your mom uses to bake
those chocolate chip cookies you love. But the cookie sheet has much, much
more aluminum (maybe 20 times as much aluminum) to retain the oven heat.
Plus the cookies are cooking at around 400 F, so the starting temperature
when removing the aluminum from the oven is much higher. Your mother knows
that she has to use a hot pad holder with a heated cookie sheet or she will
get a bad burn.
Great observation, Zack. And save a slice of bread or two for me.
Buttered french bread is my favorite.
(Note: some people learning about radiation heat transfer might get
confused by the fact that the aluminum foil is a highly reflective surface,
thinking it might remain at a lower temperature. Since the aluminum is
essentially surrounded by a black body radiator as it is enclosed by the
oven walls, it will reach the temperature of the oven, although at a
slightly slower rate than if the foil adsorbed more radiation. Maybe black
aluminum foil for more rapid heating as a new product idea?)
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Good observation, Zack, but you have reach the wrong conclusion about the
aluminum not initially being hot. Anything sitting in a hot oven tends to
reach the same temperature as the oven high. (see note at the bottom) So,
say your mother is warming up a loaf of bread (maybe with some butter
between the slices of bread) at 150 to 200 F. When the oven door opens,
that aluminum foil is at the 150 to 200 degrees as the oven. However,
notice that the aluminum foil is very thin. There is very little actual
aluminum and it is spread over a relatively large area (standard aluminum
foil is about 0.0007 inches thick; heavy duty foil is about twice as
thick). As a result cool air outside the oven cools the foil quickly. If
your mother grabs the foil with her fingers, she is relying on the cool
room air to cool the foil surface quickly to keep from burning herself.
Also her fingers themselves have a lot more mass than the aluminum foil
that they are in contact with so usually only the top surface of the skin
would be heated. Your mom's fingers might be a little toughened from all
of her work buttering that bread so she doesn't notice a slight bit of
damage to the surface layer of cells. Also, if her hands are damp, the
water on the surface of her hands will also cool the foil.
There isn't anything magic about the thin aluminum. If the bread were
wrapped in paper, you could also handle it directly from the oven. The
paper would, in fact, be less likely to burn your mom's fingers than the
aluminum, since it doesn't conduct heat nearly as well. (Unless of course
your oven temperature is set too high and the paper starts on fire - but
that is another story!)
The aluminum foil surrounding the bread is exactly the same material with
the same properties as the aluminum cookie sheet that your mom uses to bake
those chocolate chip cookies you love. But the cookie sheet has much, much
more aluminum (maybe 20 times as much aluminum) to retain the oven heat.
Plus the cookies are cooking at around 400 F, so the starting temperature
when removing the aluminum from the oven is much higher. Your mother knows
that she has to use a hot pad holder with a heated cookie sheet or she will
get a bad burn.
Great observation, Zack. And save a slice of bread or two for me.
Buttered french bread is my favorite.
(Note: some people learning about radiation heat transfer might get
confused by the fact that the aluminum foil is a highly reflective surface,
thinking it might remain at a lower temperature. Since the aluminum is
essentially surrounded by a black body radiator as it is enclosed by the
oven walls, it will reach the temperature of the oven, although at a
slightly slower rate than if the foil adsorbed more radiation. Maybe black
aluminum foil for more rapid heating as a new product idea?)
<!--END-->
This is fascinating.
Much more so than why Morehead State's Center will be schooled by the Eastern Kentucky big man.
Though I hear Morehead State's starting point guard wraps himself in tin foil before the game. Therefore, this thread should be removed from the RR and put back into College Hoops.
Much more so than why Morehead State's Center will be schooled by the Eastern Kentucky big man.
Though I hear Morehead State's starting point guard wraps himself in tin foil before the game. Therefore, this thread should be removed from the RR and put back into College Hoops.
I think this quote sums up this thread, not excluding myself:realtongu
