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Old 08-20-2015, 11:13 AM   #71
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Originally Posted by dcSaute View Post
here's the scientific facts on aluminum, cast iron, etc.
https://www.engineersedge.com/properties_of_metals.htm

aluminum does in fact "hold heat" better than cast iron - that's the Specific Heat column.

aluminum will "hold" 0.24 BTU per pound of aluminum for each Fahrenheit degree it is heated.

cast iron is only half as good at "holding heat" -
cast iron will "hold" 0.12 BTU per pound of cast iron for each Fahrenheit degree it is heated.

so, an aluminum griddle/pan must weigh twice as much as a cast iron griddle/pan in order to "hold" the same amount of heat energy.

That would be great if an aluminum pan actually weighed twice as much as a a CI pan. In real life, an aluminum pan would weigh a fraction of what a CI pan weighs so it would be less able to hold heat that the heavier CI pan.
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Old 08-20-2015, 12:05 PM   #72
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I should drink more coffee before posting stuff....I got distracted trying to be p.c. in the language / expression / etc.

as one will notice, the concluding sentence of my post is in reverse - heated to the same temperature, a pound of aluminum will hold twice the BTU heat energy of a pound of cast iron.

the glitch is, few - if any - aluminum pans of similar size approach half the weight of a cast iron pan. cast iron is 2.65 times 'denser' than aluminum - given similar construction, to achieve equal weight, the aluminum pan would need to be 2.65 times "thicker" -

to achieve equal "heat holding capacity" - half of that or 1.33 times thicker than cast iron - and that's just an unlikely design - with the possible exception cast aluminum stuff from the 1940's-50's. my MIL had "Club" brand that was fairly thick.

the thermodynamic properties on that site apply to the "pure" metal. aluminum cookware is an alloy - and manufacturers typically don't reveal the technical specifics, so without taking the pan to a lab for analysis and testing it is rather more than a lot not possible to make more 'accurate' statements than comparatives.
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Old 08-20-2015, 12:29 PM   #73
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Originally Posted by dc2123 View Post
I've been looking up some things about them on google, but everyone has a different opinion on everything.
And you thought everyone on Google had a different opinion?
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Old 08-20-2015, 01:00 PM   #74
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Interesting. The only aluminum I have is skillet coated with Teflon.
Some years ago (20+) a family member bought me a set of commercial Calphalon pans. I was sold and have added and deleted from the collection over the years. One reason why I like to buy individual pieces instead of sets.
But hands down, I prefer the AL to the CI.


Quote:
Originally Posted by dcSaute View Post
I should drink more coffee before posting stuff....I got distracted trying to be p.c. in the language / expression / etc.

as one will notice, the concluding sentence of my post is in reverse - heated to the same temperature, a pound of aluminum will hold twice the BTU heat energy of a pound of cast iron.

the glitch is, few - if any - aluminum pans of similar size approach half the weight of a cast iron pan. cast iron is 2.65 times 'denser' than aluminum - given similar construction, to achieve equal weight, the aluminum pan would need to be 2.65 times "thicker" -

to achieve equal "heat holding capacity" - half of that or 1.33 times thicker than cast iron - and that's just an unlikely design - with the possible exception cast aluminum stuff from the 1940's-50's. my MIL had "Club" brand that was fairly thick.

the thermodynamic properties on that site apply to the "pure" metal. aluminum cookware is an alloy - and manufacturers typically don't reveal the technical specifics, so without taking the pan to a lab for analysis and testing it is rather more than a lot not possible to make more 'accurate' statements than comparatives.
Happy to see you corrected the mistake. Saved me from having to look it up.
I never gave much thought to "holding heat" as I was much more concerned with how fast the pan got hot.
I guess we now know the AL heats faster and holds heat longer than CI.
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Old 08-20-2015, 02:11 PM   #75
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Hold on. If AL has high thermal conductivity it would have to work the same in both directions. That is, if AL heats up faster than CI, it has to lose heat faster than CI as well.

The specific heat figures are not responsive to AL vs CI pans as there is a huge weight difference. You're not comparing apples to apples.
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Old 08-20-2015, 02:18 PM   #76
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oh dear.

aluminum transmits heat faster by coefficient. almost three times as fast.
pure aluminum, that is. aluminum alloys do not transmit so fast - their performance is less, up to 50% less.

however, the coefficient is defined by how much heat energy passes through a plane at right angles/ normal to the flow of the heat energy.

in the shape of a pot/pan that boils down to the thickness of the bottom.
again, most aluminum construction is not as thick as cast iron.

I've had old style Calphalon that was thick; the newer stuff, not so much.

the thickness and mass factors are why discussions of aluminum vs cast iron go in circles of ever decreasing diameter until they spin into nothing. it seems everyone's experiences are different simply because "cast iron" and "aluminum" as the primary determining factor are in fact not the primary determining factors.

here's a pix of a slant logo Griswold from a century ago, vs. a month old Caphalon fry pan.

that era Griswold is 'famous' for being thin and lightweight. it weighs 3 lbs
the Caphalon is roughly half as thick - weighs 2 lb 0.125 ounces
(I'm not going to remove the handles for this....)

modern day Lodge (for example) pans of that size weigh roughly twice as much as the old Griswold, and they are thicker. the mass of today's cast iron is why so many people dislike it - it is heavy. (some of) the old stuff, not so heavy.

all that aside, the folk lore experience is that cast iron holds heat better than aluminum and takes longer to heat up, and even longer to heat up "evenly."

whether it is right or wrong depends on the exact cookware involved - but that is in fact the "legend" and there are very sound explanations as to why that legend evolved.
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Old 08-21-2015, 12:05 AM   #77
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Originally Posted by dcSaute View Post

all that aside, the folk lore experience is that cast iron holds heat better than aluminum and takes longer to heat up, and even longer to heat up "evenly."

whether it is right or wrong depends on the exact cookware involved - but that is in fact the "legend" and there are very sound explanations as to why that legend evolved.
I'll go a long with the takes longer to heat up evenly. The grill pan replacement for the center grate on my gas range is recommended to preheat for at least 10 minutes before cooking a steak or pork chop on it. I usually give it 12-15 minutes to be sure, and it does a great job.

Since I don't have an aluminum one to compare it to, I can't say for sure, but if I did the same preheat with any of my nonstick aluminum pans, I'd burn the coating right off. All that long preheat does with the grill pan is just slick up the seasoning.
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Old 08-21-2015, 07:40 AM   #78
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Hold on. If AL has high thermal conductivity it would have to work the same in both directions. That is, if AL heats up faster than CI, it has to lose heat faster than CI as well.

The specific heat figures are not responsive to AL vs CI pans as there is a huge weight difference. You're not comparing apples to apples.
Andy, that is spot on! A lot of electrical equipment use aluminum as a "Heat Sink", since it is an economical means of dispersing excess generated heat. I would think that when you want heat retention in cooking, CI would be the most economical, requiring less energy to maintain an even cooking temp at a lower stove/oven setting than aluminum, which loses heat more rapidly. Of course, gold is much better.

A little OT, but can you freeze to death in 80F water?
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Old 08-21-2015, 08:23 AM   #79
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Aren't most aluminum pan interiors coated?
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Old 08-21-2015, 11:16 AM   #80
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Quote:
Originally Posted by Andy M. View Post
Hold on. If AL has high thermal conductivity it would have to work the same in both directions. That is, if AL heats up faster than CI, it has to lose heat faster than CI as well.
The specific heat figures are not responsive to AL vs CI pans as there is a huge weight difference. You're not comparing apples to apples.
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Originally Posted by CraigC View Post
Andy, that is spot on! A lot of electrical equipment use aluminum as a "Heat Sink", since it is an economical means of dispersing excess generated heat. I would think that when you want heat retention in cooking, CI would be the most economical, requiring less energy to maintain an even cooking temp at a lower stove/oven setting than aluminum, which loses heat more rapidly. Of course, gold is much better.

A little OT, but can you freeze to death in 80F water?
I agree with both of you and was trying to be funny when I made the last statement.
For AL to heat faster, physics say it must also lose heat faster. Good example Craig in regards to electrical uses for AL. Not only do we use AL heat sinks, we use wire made of aluminum.
Now that you guys got me thinking, maybe this quicker cool down on the AL cookware might just be another great reason to use AL.
Heat up fast and cool off fast. To me, thats what a good pan should do.

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Aren't most aluminum pan interiors coated?
Not all. Calphalon anodized is not coated with a non stick material. But its anodized and I am not certain what that means. They are not bright AL, but look almost black or dark gray.
If you ever watched them make scrambled eggs at Waffle House, they are using a AL bright uncoated pan. Nothing sticks.
I did notice in one WH, they were using a CI small fry pan for eggs.

Good discussion.
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