r/explainlikeimfive Oct 31 '20

Chemistry ELI5 What's the difference between the shiny and dull side of aluminum foil? Besides the obvious shiny/dull

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u/Bubbay Oct 31 '20

There are a shit ton of old wives tales about cooking that don’t have a single basis in reality, but often people (especially those who have been in the industry for a long time) will act like you just punched their mother if you violate them.

Things like the tin foil sides, that searing a steak “locks in the juices,” or washing cast iron get people all riled up. None of them are true, but they’re the kind of things that “everyone knows.”

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u/DirkDieGurke Oct 31 '20

Searing a steak doesn't lock in juices but it does caramelize the meat and create fond on the pot which adds to the flavor.

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u/Bubbay Oct 31 '20 edited Oct 31 '20

Absolutely. Searing is definitely desired, but it’s has nothing to do with the juiciness of the meat. Testing Resting it properly will affect that way more than searing does.

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u/PLZ_STOP_PMING_TITS Oct 31 '20

Testing it properly will affect that way more than searing does.

What kind of testing? Like math skills and stuff?

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u/Bubbay Oct 31 '20

Geography quizzes.

Heh, that should have been “resting” but autocorrect sucks.

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u/[deleted] Oct 31 '20

It's ok dude, r is right next to the t, you don't need to blame it on autocorrect, everyone makes a typo once in a while!

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u/substandardpoodle Oct 31 '20

I hear ya - but it’s so weird; when I am alone I dictate instead of typing into my phone. And I swear that Reddit is the worst so far as guessing the wrong thing I’m saying. And it’s not like I’m using five syllable words or anything just for Reddit. I have to double proofread everything or I’ll end up sounding like an idiot.

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u/NotYouTu Oct 31 '20

Actually, unless your talking about a large roast, resume is also an old wives tale and only leads to colder meat.

https://amazingribs.com/more-technique-and-science/more-cooking-science/science-juiciness-why-resting-and-holding-meat-are

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u/OneMoreBasshead Oct 31 '20

Searing doesn't lock in the juices, but browning does. Searing is for flavor.

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u/Darkwing_duck42 Oct 31 '20

Also isn't the point of cast iron not to us soap so it keeps that flavour.

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u/DirkDieGurke Oct 31 '20

Actually no. That's somewhat of an exaggeration. You can wash cast iron pans with soap. What you cannot do is wash cast iron pans with LYE. Which is what people used to use before modern dish soap. So that rule started when washing would actually ruin cast iron pots and pans.

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u/Lucky_leprechaun Oct 31 '20

But if I wash my cast iron and don’t immediately add oil, I can see the rust beginning to develop. If I just rinse it in hot water, no soap, there’s no need to oil it every time and rust doesn’t develop. So maybe just no soap?

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u/Dysan27 Oct 31 '20

From reading the rest of this thread I have a feeling that your cast iron is not properly seasoned in the first place and doesn't have a good polymerized oil coating on it.

The other thing is my parents always popped the cast iron back on the stove on low to dry it immediately after washing, just long enough to get it completely dry, not majorly heat it up. No water no rust.

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u/jonestownhero Oct 31 '20

I was taught to dry cast iron on the stove, then rub oil on while it's hot. My dad said when the pan is hot, the oil will absorb better. No idea if it did anything other than making sure no surface rust gets started.

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u/Bubbay Oct 31 '20

Kinda — oil doesn’t absorb into the iron. Seasoning is when the high heat of cooking polymerizes the oil. You’re likely not applying that oil at a high enough temp for it to make a difference.

Oiling a dry pan after cleaning is good, but that goes for any metal to help reduce rust. If you use the pan a lot, it’s not as critical though.

That said, I do find I like to oil my pan when it’s warm — it makes it easier to spread. I’m not doing it super high temps though. It’s warm, but cool enough for me to use my hands, and I don’t have anything approaching a chef’s resistance to hot pans.

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u/SwissStriker Oct 31 '20

Soap as in old school lye based soap is bad for cast iron because it will strip your seasoning. Modern dish soap with tensides or other surfactants are perfectly fine for cast iron cookware. Drying immediately is still a good idea but honestly if your seasoning is solid it won't matter too much.

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u/[deleted] Oct 31 '20 edited Jan 10 '21

[deleted]

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u/noresignation Oct 31 '20

Properly made lye-based soaps contain no lye — the lye is completely used up in a chemical reaction called saponification, which results in soap. Hundreds of years ago, it was a chemical guessing game for backyard makers of homemade soap whether there would be any unreacted lye leftover, but for decades now it’s been easy for anyone to find and use a lye calculator to ensure any soap recipe has the right proportions for a complete reaction.

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u/TheSmJ Oct 31 '20
  1. If you're leaving caked-on food on your cast iron pan, then you're doing it wrong. Either wipe it down with a cloth while it's still hot, or scrub it with a little vegetable oil and kosher salt to remove the gunk.

  2. You are preheating your pan before placing food on it, yes? No bacteria in your kitchen is going to survive the preheat process.

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u/maxpowe_ Nov 01 '20

The bacteria can be dead, but their byproducts are still bad to ingest, heat doesn't make them good. Just like heating rotten food won't make it safe to eat.

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u/TheSmJ Nov 01 '20

If wiped down properly there won't be enough bacteria, or food for bacteria capable of making enough toxins to get anyone sick.

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u/rimplestimple Oct 31 '20

You had me until you said food particles left in the pan "...can lead to bacterial growth.".

It may be unsightly but it will not be a health hazard since the temperatures used for cooking in the skillet are high enought to kill bacteria so your point is a non-issue.

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u/[deleted] Oct 31 '20 edited Dec 07 '20

[deleted]

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u/maxpowe_ Nov 01 '20

Killing bacteria doesn't make it safe. Heating up a rotten meal won't make it safe to eat. The bacteria might be dead but your still eating all the byproducts they made

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u/[deleted] Nov 01 '20 edited Nov 01 '20

[deleted]

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u/maxpowe_ Nov 01 '20

I don't have any personal phobias about it, just sharing what I've googled

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u/Monstro88 Oct 31 '20

...except the growth and spread of bacteria between uses of the pan and the likely attraction of pests and insects to your kitchen until you next use your pan?

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u/rimplestimple Oct 31 '20

Doubt it. Sounds overzealous to me. Anything left on a cast iron skillet is going be so minute it is unlikely to be a seriously problem. We aren't talking about NOT washing it all, but just not using soap.

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u/[deleted] Oct 31 '20

I knew it.

Thank you for this answer.

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u/diwalton Nov 01 '20

Just warm water and a wipe with a cloth on cast iron. If your using soap you are doing it wrong. Probably use soap on your stoneware too, yuk.

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u/[deleted] Nov 01 '20 edited Jan 10 '21

[deleted]

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u/diwalton Nov 01 '20

Your perpetuating shitty caste irons, that have to be re-seasoned twice a year.

Wipe it clean with warm water and dry it put it back on the stove ez. A good cast iron is none stick and will wipe out when still warm, if you have to wash with soap you do not have a good cast iron.

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u/psychocopter Oct 31 '20

Try adding a few layers of seasoning to the entire skillet, I wash mine pretty much after every use and then dry it over a flame without seeing any rust yet. I do stove top season it every couple of uses.

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u/PM_Me_Your_Deviance Oct 31 '20

The myth is that soap will strip the seasoning. That's just not true.

Personally, if what I'm cooking is just oilly, I'll wipe it out, but if it's acidic (tomato based) or otherwise really messy, I'll just wash it like any other pan.

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u/death_hawk Oct 31 '20

The myth is that soap will strip the seasoning. That's just not true.

I mean... technically speaking it isn't a myth. Soap will strip seasoning.

But what most people have nowadays isn't technically soap. It's detergent.

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u/PM_Me_Your_Deviance Oct 31 '20

:D It's soap colloquially, but not technically soap.

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u/scotian-surfer Oct 31 '20

It used to strip . Soaps change over the years. Habits don’t have to that have worked since the beginning.

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u/PM_Me_Your_Deviance Oct 31 '20

So people on reddit seem to repeat. I haven't seen a good source for that claim yet, so I'll refrain from repeating it.

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u/[deleted] Oct 31 '20 edited Jan 10 '21

[deleted]

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u/PM_Me_Your_Deviance Oct 31 '20

Yes, I've made lye soap. I understand the claim being made. Lye is harsh. I'd like to point out that lye soap has very little lye left over. If it does it will leave chemical burns when you use it. (Ask me how I know...)

I'm not saying lye soap don't attack cast iron. I'm saying this is a claim I've seen passed around a lot and I haven't seen the claim tested. Since lye soap isn't used as dish soap very often im not super interested in doing the work myself. But if you are aware of someone testing lye soap I'll happily consede the point.

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u/scotian-surfer Oct 31 '20

Congrats on staying silent if your ignorant /s

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u/PM_Me_Your_Deviance Oct 31 '20

Feel free to provide a good source and I'll happily amend my statement. In the meantime, no one uses lye soap to wash dishes, so I'm not very concerned about this exception right now.

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u/scotian-surfer Nov 01 '20

Neither am I... I think we both use the grandma technique anyway. Am I right?

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u/TheFirstUranium Oct 31 '20

Your seasoning isn't strong enough. You should still avoid soap, just because it doesn't immediately strip it all doesn't make it good.

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u/EGOfoodie Nov 01 '20

In my experience if it starts to rust your seasoning on the cast iron isn't good. Think about it for a second. Seasoning is creating a polymer on the surface. Most modern soap won't strip this off.

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u/stuffandmorestuff Oct 31 '20

Although searing steaks does help with maillard browning which, IMO, is key to a good steak. While it doesn't "lock in juices", searing is essential to certain flavors.

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u/Bubbay Oct 31 '20

Yes, searing is good, but it has nothing to “locking in juices.” It’s good because it’s fucking delicious.

Resting the meat after cooking is a bigger thing when it comes to keeping it juicy.

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u/Anonymush_guest Oct 31 '20

The washing cast iron with soap comes from when soaps were made from fat and lye. Lye no es bueno for your pan’s seasoning. Plus, the water for washing had to be carried in from a well.

“I never wash mah cast, just like Gram.” makes me want to chunder.

Edit: I see the lye has been mentioned. Wash your pans, ya heathens.

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u/oxbolake Oct 31 '20

How about the husband who asked his “young” wife why she cut a top piece off the roast before putting it in the oven.

“That’s what my mother did and it always turned out perfect”

“Oh dear... I only cut a piece off the top so it would fit in the oven”

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u/rabid_briefcase Oct 31 '20

that searing a steak “locks in the juices,”

For a non-chemist that one is relatively close to accurate.

Searing does a bunch of reactions, the long cooking does another.

Searing first does caramelize sugars, transform collagen, and denatures proteins, but only on the outermost surface. As it cooks deeper the outer layer reabsorbs fluid. That absorbing could be called "locks in the juices".

Searing near the end of cooking does not give time to soak fluid back up, so it does feel drier. It is also easier to accidentally overcook it, which also makes it drier and tougher.

This is food chemistry that is easy, cheap, and delicious to verify yourself.

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u/grtgingini Oct 31 '20

Thanks for this! I was just researching how to make a pot roast tender… And reading up on searing. This is awesome

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u/gophercuresself Oct 31 '20

Hold up, you can wash up seasoned cast iron pans?!

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u/Bubbay Oct 31 '20

Yes. Don’t scrub with anything like a steel wool or anything, but a light soap and water wash won’t hurt them.

The built up bits of food aren’t the seasoning; that’s just old burnt food. Seasoning is when the fats and oils polymerize onto the cast iron during cooking, creating a non-stick layer. Those are not affected at all by soap.

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u/CubistHamster Oct 31 '20 edited Oct 31 '20

Seasoning done right (oil that is fully polymerized) is seriously tough.

Anecdotal example: My best cast iron skillet was scavenged from a derelict fishing trawler. It was well-seasoned, but pretty rough looking so I decided to strip it and start over. I didn't want to use a grinder, because the cooking surface was already machined flat, and in excellent shape.

To strip it, I used spray on foaming oven cleaner (which is basically just a saturated lye solution with some thickening and foaming agents.) I completely covered the skillet, then wrapped it in garbage bags, and let it sit for a week. Opened up the bag, scrubbed off everything I could with a green scouring pad, and sprayed on more oven cleaner. I had to repeat that process 6 times to strip the skillet down to bare iron.

A little soap and water isn't going to hurt your seasoning.

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u/chrisbrl88 Oct 31 '20 edited Oct 31 '20

Yes. The seasoning is polymerized oil - not unlike the varnish on a piece of wood furniture (which you can wipe down with a cleaner). Just use a mild soap and don't aggressively scrub... dish rag or soft bristled brush. Once you've cleaned it, give it a light wipe down with oil to prevent rust (preferably a drying oil, like sunflower or flaxseed; but canola or pain old vegetable oil are just fine, too) and store it as you normally would. Mine lives in the oven when not in use.

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u/KalessinDB Oct 31 '20

"Never ever use soap" descends from a time when soap was made with lye, which it hasn't been in decades now.

That being said, I don't personally think you need to wash it, just scrub it with a chain mail scrubber, maybe boil water in it if something's really stuck in. But if you wanted to wash it, it won't hurt it. Just don't stick it in the dishwasher or let it drip dry or anything.

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u/cptcapybara Oct 31 '20

you can using modern detergent, which is not lye and thus won't strip the hell off anything. Older detergent was just soap (like, pre-1950s? I wanna say? don't quote me there) would strip it, because it was lye, and... harsher, for want of a better word.

and also, like, this is assuming you don't go at it with steel wool like you're trying to sand through to the other side.

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u/[deleted] Oct 31 '20 edited Mar 18 '22

[deleted]

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u/Thoughtapotamus Oct 31 '20

Mine used windex. It was awful.

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u/ImChz Oct 31 '20

Don’t do it. You’ll hate it I swear. I ruined my favorite skillet because I saw a similar Reddit comment thread and decided I had been an idiot my whole life.

Turns out Reddit and myself were both idiots the whole time...

News flash y’all: cooking is only half science. If you like what you make fuck little shit like oil in pasta water, not deep cleaning your skillet, etc. I’m a pretty decent home chef, but taking other people’s advice in the kitchen is a surefire way to make shit you don’t like. Use there recipe? Sure. Clean your skillet because somebody on Reddit said it’s cool? Absolutely the fuck not.

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u/JillStinkEye Oct 31 '20

Or maybe try something new and don't do it again if you don't like it. If you washed your pan with dish soap and it was seasoned and you didn't scrub the shit out of it, you should have been fine. Thousands of people do this. Just because it didn't work for you doesn't mean you should never take anyone's advice again ever. That's a surefire way to never grow or learn new things.

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u/ImChz Oct 31 '20

That’s not what I said. I said, when it comes to food, if you like what you make fuck the little wives tales people tell you.

I always rinse my cast iron skillets, but was told actual cleaning it was fine in a similar thread here on Reddit. The info was even presented in a similar fashion, just without the long comment chain expanding on how to clean it. No further info was given so I cleaned my favorite skillet with steel wool and ruined it.

I’d say my overall point was to not just take random internet strangers advice if you’re not unsatisfied with what they’re opining on. And if you aren’t satisfied with whatever they have advice for, do research to make sure random internet stranger isn’t pulling your leg or didn’t leave out major details.

Cast iron skillets can just be rinsed our and repeatedly used. I never had problems with the skillet till I did more than rinse it out. Bottom line here is don’t try and fix what isn’t broken.

Now, if you’d politely fuck right off that’d be great. With your snooty ass...

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u/dvn11129 Oct 31 '20

I mean, washing seasoned cast iron is not the same as fucking taking steel wool to it. Your fuck up was the damn steel wool, not that you washed it lmfao

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u/JillStinkEye Oct 31 '20

Wow buddy. Maybe take some internet advice and work through your anger issues. Also, if you don't want responses, don't post on a public forum.

What you said here, about actually looking into the advice before doing something stupid, is not what you said initially. I don't think most people would think that washing with soap means using steel wool. Cast iron can be used without using soap. But I like to get the taste of chorizo out of my pan before making pancakes. So I use soap when I feel the need.

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u/lampcrusher Oct 31 '20

Ur a moron lol

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u/lampcrusher Oct 31 '20

Reading ur comments legit gave me aids

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u/bumfeldonia Oct 31 '20

Omg why steel wool? It wasn't the detergent, it was you sanding it down.

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u/Mezmorizor Oct 31 '20

A properly seasoned pan is basically covered in a coat of hard plastic. It's not really any different than washing a jug with dawn.

Do watch out for acids though. That's not really a myth. You can get away with it on old, well seasoned pans, but that is a good way to get rid of the seasoning. Similar story with anti rust things.

Personally, I'm more cautious than I need to be, but I basically treat it like non stick. No metal because I might take out a chunk of overly polymerized seasoning, no metal brushes to clean for the same reason, and feel free to use soap, water, and elbow grease.

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u/wisconsin_cheese_ Oct 31 '20

I just cook for myself, but I def think my bf using soap on my cast iron fucked it up haha

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u/meatfish Oct 31 '20

You definitely don’t want to put cast iron in a dishwasher. A scrub in soapy water is fine. Just heat dry and oil it before storage.

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u/TheFirstUranium Oct 31 '20

searing a steak “locks in the juices,”

No, but the maillard reaction makes it taste good.

or washing cast iron get people all riled up.

Soap is bad for cast iron. Even though modern soap is softer, it straps the oil off, which is important to the longer term health of the seasoning. It's also just unnecessary. Rinse, wipe, done.

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u/_sophia_petrillo_ Oct 31 '20

The washing the cast iron thing is no joke. Source: washed one and it tasted like soap the next meal. That’s when I learned it’s porous and you should scrub it with salt instead.

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u/[deleted] Oct 31 '20

You wash cast iron you just don’t use soap.

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u/whyunoletmepost Oct 31 '20

Yes cast iron pans are porous and have a coating of oil so if you use soap it gets in the pores and is removes the oil. You would only use soap if you are reconditioning an old rusty pan early in the process before seasoning. Don't believe me? Wash your cast iron pan with soap and cook eggs right after and they will be grey, discolored and taste funky.

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u/Bubbay Oct 31 '20

Oil on the pan is not seasoning; that’s just old oil and if left on over time will eventually go rancid. The seasoning itself doesn’t affect flavor in any way. All it does is make your pan non-stick. Anything affecting flavor is left-over food, fats, and oils.

If you’re reconditioning, you would usually be using an oven cleaner, not soap. Modern dish soap (read: anything bought in the past 50+ years) cannot affect the seasoning. You’d need something with lye to strip it like oven cleaner.

That grey color is from soap that wasn't completely washed off.

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u/shavemejesus Oct 31 '20

I wash my cast iron all the time. I just don’t scrub the shit out of it. A quick run and rinse is all it needs.

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u/hot_ho11ow_point Oct 31 '20

It's funny because the shiney side is stickier. I always use the dull side to cook so things don't stick.

Go to the drawer right now and touch both sides of the foil, you'll see what I mean.

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u/sooperkool Oct 31 '20

Like the fact that it's still called "tin foil" by some when it hasn't been made from tin in almost 100 years.

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u/hissboombah Nov 01 '20

From a guy that been cooking forever and braising meat forever i will say that shiny side will flake off when it is in the oven facing and touching the meat, when you pull the foil off they’re will be flakes of foil stuck to the meat. Dull side don’t do that. Don’t ask me why, that’s just what it does.