How come alumnum foil doesn't get hot in the oven?

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ElFenix

ElFenix

Elite Member
Super Moderator
Mar 20, 2000
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Originally posted by: DrPizza
There's more to it than the rate at which it cools. NOT because it cools down quickly..

But rather, because it has a low specific heat. Thin aluminum foil simply doesn't hold enough heat at 450 degrees (F) to burn you.
Click to expand...
bingo


sue did take a long time for the correct answer to appear. this is ATOT though.
 
D

dighn

Lifer
Aug 12, 2001
22,820
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81
Originally posted by: ElFenix
Originally posted by: DrPizza
There's more to it than the rate at which it cools. NOT because it cools down quickly..

But rather, because it has a low specific heat. Thin aluminum foil simply doesn't hold enough heat at 450 degrees (F) to burn you.
Click to expand...
bingo


sue did take a long time for the correct answer to appear. this is ATOT though.
Click to expand...

it had been said before, just not so precisely
 
D

dxkj

Lifer
Feb 17, 2001
11,772
2
81
Originally posted by: DrPizza
There's more to it than the rate at which it cools. NOT because it cools down quickly..

But rather, because it has a low specific heat. Thin aluminum foil simply doesn't hold enough heat at 450 degrees (F) to burn you.

Space shuttle tiles: Hold a LOT of heat, cool very slowly, but won't burn you.
Steam sprayed on you: can start out at well above 212 F, but cools very quickly to 212 when it's sprayed on skin. Burns severely.
Click to expand...

This is just a further explanation of cools quickly.

When you touch it, it cools down to the temperature of your hand quickly because it doesnt store enough heat to stay warm.

AKA it cools quickly! whether from air or your hand
 
H

Howard

Lifer
Oct 14, 1999
47,982
11
81
Very low thermal mass.

Aluminum is lightweight and has a low specific heat capacity. The human hand has a lot of water in it, which has a high specific heat capacity. Our hands detect temperature, not heat energy.
 
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Turkey22

Senior member
Nov 28, 2001
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Well it definitely takes longer than 5 seconds to cool down as I have burned myself on foil before and had it be very warm to the touch many other times as well.
 
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torpid

Lifer
Sep 14, 2003
11,631
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Originally posted by: Turkey22
Well it definitely takes longer than 5 seconds to cool down as I have burned myself on foil before and had it be very warm to the touch many other times as well.
Click to expand...

 
GasX

GasX

Lifer
Feb 8, 2001
29,033
6
81
fold it over 10 times bake it for an hour and hold it against your eyeballs and see how that works out for you...
 
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tikwanleap

Senior member
Oct 9, 1999
922
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Originally posted by: dxkj
Originally posted by: DrPizza
There's more to it than the rate at which it cools. NOT because it cools down quickly..

But rather, because it has a low specific heat. Thin aluminum foil simply doesn't hold enough heat at 450 degrees (F) to burn you.

Space shuttle tiles: Hold a LOT of heat, cool very slowly, but won't burn you.
Steam sprayed on you: can start out at well above 212 F, but cools very quickly to 212 when it's sprayed on skin. Burns severely.
Click to expand...

This is just a further explanation of cools quickly.

When you touch it, it cools down to the temperature of your hand quickly because it doesnt store enough heat to stay warm.

AKA it cools quickly! whether from air or your hand
Click to expand...

Yep.

Specific Heat tells you how much heat a given material can hold. Aluminum has low specific heat so at 450 degrees, a given amount of aluminum stores x amount of heat energy. The same amount of water (Which has a much higher specific heat) will store y amount of heat. Therefore x will be smaller than y.

Another factor to consider is that aluminum is also a good heat radiator. That's why they're used in heatsinks.

And the final thing is that foil is very thin, so the surface area to mass ratio is high. In other words there is alot of material exposed to air to allow a greater heat transfer rate. Heatsinks are also designed with this principle in mind with all the fins they put on them.

All these factors combine to give the impression that aluminum foil cools quickly out of the 450 degree oven....
 
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djheater

Lifer
Mar 19, 2001
14,637
2
0
Originally posted by: Argo
I thought metals were supposed to be good conductors of heat?
Click to expand...

You were able to answer your question within your question, and still didn't understand. I doubt we can help you with this.
 
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