# Does a foil wrapped potato cook faster?



## cookfab (Jan 22, 2013)

Does a foil wrapped potato cook faster than an unwrapped potato in an oven?


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## petemccracken (Sep 18, 2008)

Faster? I'm not certain.

What I AM certain of is that a foil wrapped potato _steams_ rather than _bakes._


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## berndy (Sep 18, 2010)

No, it takes time for the heat to get thru the foil!


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## petalsandcoco (Aug 25, 2009)

Foil is a conductor of heat, would it cook a potato faster ? I would believe so. How much faster ? Who knows ? It probably shaves 10-15 minutes off the cooking time. 
I agree with Pete, it is steamed . 
The textures of the flesh of the potatoes are very different. I find the foil wrapped are softer in texture whereas the other is granular (right word ? ) feel .


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## allanmcpherson (Apr 5, 2007)

Yeah, it cooks faster, no question. Its the same principle as the stall in bbq. What the foil does in inhibit surface evapouration, or cooling. As your spud cooks it lets off water through evapouration, cooling the surface on the skin. Same way we sweat while running. Picture running in a rain coat, thats what the foil does. You still sweat, but you actually get hotter. 

As far as Pete's comment goes, right on the money. You get a similar effect to foil by bathing the potato in oil, without sacrificing the intense flavour of roasting. Bonus points for roasting skin on potatoes ina salt crust.

Al


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## siduri (Aug 13, 2006)

For me, you might as well just boil it as bake it in foil.  Not quite the same but definitely doesn't bring the qualities that you want in a baked potato - nice somewhat chewy skin, drier interior that sops up butter or sour cream.   But yes it's faster but no, it's no longer really a baked potato!

I read somewhere, and it made sense, to put a metal skewer through the potato to conduct some heat into the center.  I've never tried it, but I wonder if anyone here ever has. 

When i'm in a hurry, i put them in the microwave (mine has many settings, including oven and grill) and put the microwave to the minimum (90) and the oven to the maximum (450) and it makes a quick baked potato that is certainly better than the ones in foil.


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## flipflopgirl (Jun 27, 2012)

The micro makes a great "preheater" (is that a word) for lots of things, but had never thought of using it for bakers.

Great tip, Siduri.

I like to oil a few nice russets, roll in cracked salt and pepper and then toss on my pizza stone to bake.

The crust turns out nice and crispy.

mimi


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## petalsandcoco (Aug 25, 2009)

siduri said:


> I read somewhere, and it made sense, to put a metal skewer through the potato to conduct some heat into the center. I've never tried it, but I wonder if anyone here ever has.


A test was done :

http://blowers.chee.arizona.edu/cooking/heat/potato.html


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## ed buchanan (May 29, 2006)

Yes!!

Only1 problem ,now its not baked its 1/2 steamed. because you are not letting steam out that forms when heat meets liquid content of potato

     . To bake correctly wash, punch a hole or 2  oil it and if possible bake it at 400 on a rock salt base. Comes out great all the time and taste  like a baked potato used to taste like.


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## maryb (Mar 21, 2008)

Never foil, never microwave a baked potato, ruins the skin and the texture. I love to wash them, sprinkle with S&P then toss on the smoker


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## thefloatingchef (Apr 29, 2013)

siduri said:


> I read somewhere, and it made sense, to put a metal skewer through the potato to conduct some heat into the center.


I myself have done this.. But don't know if it cooked any quicker, as I didn't have a potato with out a skewer through it to see the diff.


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## koukouvagia (Apr 3, 2008)

I get great results by par boiling the potato first, helps retain moisture. Then I smear with olive oil and salt and wrap in foil before placing directly into the ashes. The skin comes out perfectly brown and crisp and the inside is creamy and fluffy.  Sometimes no foil and place directly on the grate.  I don't put them in the oven, what's the point?


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## kuan (Jun 11, 2001)

I cheat.  At home I microwave it, then coat in olive oil, s+p, the roast it at high heat.


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## dcarch (Jun 28, 2010)

Space satellites are wrapped in reflective foil to reject solar heat.

Aluminum is a very good reflector of infrared (heat).

dcarch


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## kuan (Jun 11, 2001)

Yeah?  But does it reflect more heat than it retains?


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## boar_d_laze (Feb 13, 2008)

Why speculate on cooking times?  If you can't find a trustworthy source like McGee, go empirical.  Potatoes and aluminum foil are cheap enough.  Get twenty pounds of bakers, divide them into lots by size, split each lot in half, wrap one half in aluminum foil, and bake them, ten lbs at a time.  In a couple of hours, you'll have a large enough data set to know what bakes faster and/or tastes better to within a standard deviation. 

Speculatory inference based on poorly remembered magazine articles and high school physics is speculatory inference based on poorly remembered magazine articles and high-school physics. 

BDL


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## jersey lane (Feb 25, 2013)

Let's say yes it does cook faster but don't serve one to an Irish chef.  I like the texture of the oven baked potato crisp skin and a powdery interior with the pungent aroma that escapes when the spud is opened.  The foil baked retains a little too much moisture and the flesh remains firm, the skin a little slimy for my visual liking and not so pleasant to eat. For me a component of a simply baked potato is the eating of the skin. In classical cooking we used to bake the potato on a bed of coarse salt to aid cooking.  I expect this is a similar mechanical process as baking bread on cornmeal. When in London last year one of my renowned baker buddies assured me that the cornmeal enhanced cooking time cooling time and inhibited browning on the underside. The miniature baked potatoes I have posted on my web page at stinsoncatering.webs.com were all free baked.  What a subject, now we should ask when using foil what's best shiny side in or out, good luck with that one!


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## dcarch (Jun 28, 2010)

Google Image "Fireproof suit"

You will see they are made of reflective material. Not Speculatory inference of high school physics, IMHO.

Next to silver, I believe aluminum has the highest heat reflecting property.

dcarch


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## siduri (Aug 13, 2006)

dcarch said:


> Google Image "Fireproof suit"
> 
> You will see they are made of reflective material. Not Speculatory inference of high school physics, IMHO.
> 
> ...


One thing is a reflective material at a distance from the body, with some sort of padding, another is to be wrapped in foil in contact with the body. And if aluminum is not a good conductor, then maybe i should throw out all my aluminum-base pans?

Besides, steam cooks things very quickly, and so the wrapping in aluminum foil keeps the steam inside, as others have said. There's not just the contact heat but also the steam. Without the foil the steam escapes. Steam is hotter than water, and in contact with the inside of the potato. If you didn't have the problem of melting or burning, you could probably wrap it in plastic, but it would probably steam it anyway.. The steam cooks it faster, but of course, then it comes out steamed not baked. Still trying to figure out why, as koukouvagia says, if you put it in the ashes, it browns anyway, maybe because it has a direct contact with the heat source, and not just hot air around it - a guess.

Life is complex, and many factors are involved. As anyone knows who has had to deal with stupid multiple choice tests, when in doubt the longest answer is usually right, because most things are complex - as i presume are the fireproof suits. Under the layer of aluminum there are probably other layers of polymer substances that resist melting and make a layer of air surrounding the body, protecting it. I'd guess that if you wrapped the potato in several layers of newspaper and THEN in foil it would take a lot more time to cook, not less, than if you had newspaper and not foil.

BDL- there are some hypotheses, now you can go test them with your several tons of potatoes /img/vbsmilies/smilies/smile.gif.


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## ed buchanan (May 29, 2006)

Jersey Lane  chef and I are in same ballpark.  W hen baked potatoes were d\first done, there was no aluminum foil.


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## dcarch (Jun 28, 2010)

Aluminum is an excellent thermal conductor, but consider the following:

1. The so called plastic silvery “survival blanket” is thinner then paper, yet effective in reflecting heat back to your body. When you “rest” meat, you use foil to retard evaporation, also to reflect heat back to the meat. A Thermos bottle is silvered inside to reflect heat back to the water. All in direct contact with the heating body.

2. Aluminum may be a good heat conductor, but nothing can change the thermal conductivity of another material, in this case a potato. A potato will conduct heat at the same speed regardless of the container material and outside temperature.

3. Furthermore, as long as the potato has water, nothing you do can get its temperature higher than 212F. (assuming sea level atmospheric pressure). Moisture is invisible in air. When you see steam, which is water droplets, it means the temperature has dropped below 212 F.

4. That said, the excellent thermal conductivity will cause the exterior to burn faster, but the speed of the temperature rise inside the potato is governed by the conductivity of the potato. (Assuming in a very hot oven). This is a time constant and cannot be changed. That’s why you can char the outside of a steak and still have rare interior.

5. The foil will not help much in raising temperature unless it can be so tight like a pressure cooker.

6. The steaming effect with foil will mean the temperature inside the foil is no higher than 212F.

7. A microwave can get the temperature inside a potato higher than 212F due to the magnetic wave’s penetrating power and the pressure created by the firmness of the uncooked potato exterior. That’s why microwaving potatoes can sometimes explode and make a mess.

8. It also has to do with the nature of your oven. Electric oven tends to have more infrared heating, regular oven is both convection and infrared, and a convection oven is more conduction by convection.

Cooking is chemistry and physics.

dcarch


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## petalsandcoco (Aug 25, 2009)

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petalsandcoco


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DC : Fascinating info ! Thank you so much for taking the time to explain . Knowledge is power and this info is a keeper.


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## boar_d_laze (Feb 13, 2008)

With respect and apologies,

Wrapping potatoes in a layer or two of aluminum foil does not do much about the amount of heat energy they absorb, nor does it have much to do with internal temperatures. It's just not enough aluminum foil to make a difference in that respect. Baking potatoes wrapped in aluminum foil takes about the same amount of time to reach the same amount of doneness as baking unwrapped potatoes. Since other minor factors make a bigger difference, e.g., the height of the rack, deadband of the thermostat, temperature of the potato going in to the oven, etc., the effect of the aluminum in these respects is negligible.

While water has a liquid doesn't get hotter than 100C or 212F (at sea level), steam does. If the oven is hot enough, the steam will form inside a baking potato whether the potato is wrapped or not. Potato skin is a semi-permeable membrane. Potatoes explode when steam forms, and cannot cross the barrier of their skin fast enough to gradually release the pressure caused by its expansion. Enough pressure, kablooey, no pressure, big mess.

Microwave potatoes explode more often than oven cooked potatoes, but oven cooked potatoes do explode. That's why people who cook potatoes in the oven pierce them with a fork.

Microwave potatoes explode more often because more energy is transferred more efficiently in the microwave, steam is created _more quickly_, and pressure builds faster than in ordinary ovens. In other words, the _steam pressure_ within the potato is partly a function of time.

Wrapped potatoes cooked in the oven do not explode more or less often than potatoes cooked in the oven which are not wrapped. That's because wrapping the potatoes doesn't do enough to prevent steam from crossing the barrier of the skin, nor does it do it enough to allow pressure to build between the skin and foil to blow the foil off the potato. It's sufficiently effective as a low pressure barrier to keep the potato flesh and skin moist. The flesh's texture is slightly altered, and the skin remains soft and flaccid through the cooking process.

Wrapping potatoes in aluminum foil is a way of keeping already cooked potatoes from drying out when holding them. As a technique it has its limitations. If held wrapped too long, the potato dries out AND the skin loses its texture.

Most people prefer the drier flesh and crisper potato skin of a potato which has not been wrapped. Count me in.

I never wrap potatoes before oven-baking them. Instead, I rub them with EVOO, and large grain salt, and pierce them before baking. But that's me.

The interior and skin textures of microwave (baked) potatoes are more similar to potatoes which were wrapped before oven baking, than to those which went into the oven bare. But, if you nuke a potato long enough it will wrinkle up and collapse as a result of losing too much moisture. Even if you don't overcook it, let it rest for awhile after it's been removed from the microwave, it will release enough vapor to visually shrink.

I don't prefer microwave potatoes to baked potatoes but don't dislike them, and don't panic if the subject of "baked" potatoes raises its head just as the steaks are ready to go on. Neither will I shrink from a spud which was baked wrapped.

After the butter, sour-cream, chive (or onion of whatever persuasion), salt and pepper (gotta have pepper), how bad can it be? Bacon? Cheese? Chopped brisket and barbecue sauce?

BDL


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## siduri (Aug 13, 2006)

Well, nice explanations all. I admit, i passed chemistry only by the skin of my teeth. And yet, i still have the feeling the foil wrapped ones are quicker. Why i think that? I don;t know. I'd like to see the results, but don;t want to waste a good potato wrapping it. When i make stuffed eggplant they seem to cook faster if i cover them in foil, then unwrap at the end to brown. And don;t steamers cook food in steam even if not under pressure?

BDL i thought you were going to do the empirical tests and give us your results instead of all this theory/img/vbsmilies/smilies/smile.gif!


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## maryb (Mar 21, 2008)

Then there are uses for the leftovers: Smoke Baked Deep fried potato slices





  








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maryb


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## boar_d_laze (Feb 13, 2008)

> BDL i thought you were going to do the empirical tests and give us your results instead of all this theory/img/vbsmilies/smilies/smile.gif!


Been there, did that. Took notes. In ink.

I accurately described several different methods of cooking potatoes and how the results vary. The descriptions were empirically based.

The explanations I gave explain the known, empirically gathered data, while accurately predicting what anyone else will achieve using her own ovens, potatoes, foil, etc. In other words, they pass the two prong test for "scientific method." Also, _they're right_. In those ways they're a far cry from what's in some other posts.

As the Eskimos say, _genug shoyn_ /img/vbsmilies/smilies/smile.gif!

BDL


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## kuan (Jun 11, 2001)

You know when I first started that's the way I was told to do it.  I never questioned why, and that's the way it's still done in a lot of places in mid-America and it's still bad.  I still don't know why it's done.


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## ljokjel (Jul 1, 2009)

Dont know wether it is cooked faster, but i do have one reason to do it with foil.

If your intention is mash or making a pure it will be easier to peel them if they were cooked with foil. 

So yeah... Lets derail it a bit more. Potato pure: Boiled or baked potatoes? Peeled or unpeeled?


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## kokopuffs (Aug 4, 2000)

Alright, what's the recipe for foiled baked potato????  Is it pierced five or six times then foiled and placed into the oven?????


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## dcarch (Jun 28, 2010)

siduri said:


> --------I read somewhere, and it made sense, to put a metal skewer through the potato to conduct some heat into the center. I've never tried it, but I wonder if anyone here ever has. --------------


Metal pin/skewer can help conduct heat into the center of food, but not that much. The amount of heat conducted is dependent on A. Conductivity of the metal, B. cross sectional area of the pin, C. Length of the pin.

There is a technology which can conduct heat much more efficiently and which I am not sure if it has been used for food preparation. It is known as "heat pipe". You can Google "heat pipe" and find out how it works.

"Heat pipe" is used extensively in laptops to conduct heat away from CPUs. You can buy inexpensive surplus heat pipes and make your own heat pins for cooking, which I have done.

dcarch





  








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## siduri (Aug 13, 2006)

boar_d_laze said:


> Been there, did that. Took notes. In ink.
> 
> I accurately described several different methods of cooking potatoes and how the results vary. The descriptions were empirically based.
> 
> ...


MIght have known, BDL. and who ate all those potatoes?


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## ed buchanan (May 29, 2006)

A recipe for foil baked potatoes????


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## kokopuffs (Aug 4, 2000)

WHAT ABOUT FOIL WRAPPED?????????????????????????????????????????????????


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## michaelga (Jan 30, 2012)

@ dcarch

Do tell more - i'm interested.

Be careful with the selection though - it's probably not lead-free soldier.


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## kokopuffs (Aug 4, 2000)

ED BUCHANAN said:


> A recipe for foil baked potatoes????


Baked any different from nakedly baked potatos???


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## koukouvagia (Apr 3, 2008)

Ok here's a recipe.  Parboil some idahos. Using an apple corer remove place it into the end of the potato and carve a skinny tunnel down the length of the potato.  Season with salt/pepper and olive oil, and stuff with a strip of bacon and rosemary.  Roast until golden.


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## dc sunshine (Feb 26, 2007)

Koukou - yummers!  Bet they taste great.

Here's a good reason for baking in foil - keeps the campfire ash off the skin


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## ordo (Mar 19, 2009)

Koukouvagia said:


> Ok here's a recipe. Parboil some idahos. Using an apple corer remove place it into the end of the potato and carve a skinny tunnel down the length of the potato. Season with salt/pepper and olive oil, and stuff with a strip of bacon and rosemary. Roast until golden.


Oh, my. That's an idea. A simple, beautiful idea.


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## cookfab (Jan 22, 2013)

Thanks for the good answers, I learned,

ovens cook with different types of heat, electric is more radiant heat and gas is more convection
foil reflects radiant heat.
foil conducts heat better than air.
but so does potato skin.
foil may or may not capture heat better than potato skin
but the best advice is to not wrap potatoes in foil.
I am looking forward to a better baked potato, thank you.


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## koukouvagia (Apr 3, 2008)

I think if you want to wrap in foil you should.  Personally I like wrapping in foil, why not?


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## cookfab (Jan 22, 2013)

Koukouvagia said:


> I think if you want to wrap in foil you should. Personally I like wrapping in foil, why not?


I am just looking for a better way to bake or cook a potato, that increases the flavor and that does not involve frying.

I would like to possibly eat the skin.

I noticed a fast food place selling potato skins so I am thinking I may be missing something.

Does anyone here eat the skin?

*I also like stuffed baked potato so I would like to ask for advice about stuffed baked potato methods and recipes.*

*Also is there a stuffed baked potato that I can freeze?*


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## ordo (Mar 19, 2009)

These days I'm not baking skinned potatoes. Not enough crusty surface. I "casco" (crack?) the potatoes, Spanish way, mix in a bowl with salt, black pepper, cayenne pepper, rosemary and/or thyme and sunflower oil. Then I roast. Problem is that once the bottom side of the potatoes is golden and done, you must turn them one by one. Eventually add a lot of minced garlic almost at the end.


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## rat (Mar 2, 2006)

Remember too, after WWII aluminum foil was considered cutting edge much like the " molecular cuisine" today, it was rare and somewhat expensive. Potatoes wrapped in foil were considered "up there" in the restaurant world.  A funny thought.   How much of the new stuff today will be commonplace in the future...

I cooked two potatoes today @ identical weights, one in foil one without. The cook times were similar perhaps due to their placement in the oven?? The foil potato was IMO better tasting, moister and flakier, could have been the potato though.


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## petalsandcoco (Aug 25, 2009)

rat said:


> The foil potato was IMO better tasting, moister and flakier, could have been the potato though.


This is what I believe to be true as well.

I won't knock a potato cooked without foil, but the taste is definitely different.


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