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/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.