Comment by JASchilz | Hacker News Reader

Comment by JASchilz | Hacker News Reader

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When I first got into cast iron, I spent a lot of time on oven-seasoning. It turns out that your daily practice is much more important than that oven seasoning, and the two important steps are:

1. Get the oil hot before you add any foods.

2. Use a sheet-metal spatula/flipper

Humanity has known for a long time that when you get your cooking oil hot, it repels food instead of binding it to the cooking surface; but the amateur cook has forgotten because of a reliance on non-stick surfaces.

The sheet-metal spatula/flipper lets you clean the cast iron with each pass of the tool. A rubber/wooden tool will leave small, burnt on bits of food, which accumulate more bits of food; a sheet-metal tool with scrape those off before they become a problem. Also, a sheet-metal spatula will scrape the roughness of the cast-iron from the bottom of your pan over the course of decades, moving you towards that inky-black mirror of grandma's old pans.

I can cook anything on my cast iron, just by following those steps, even fried eggs: the surface is totally non-stick. And cleaning is simple too: sometimes I'll make a few passes with the spatula to scrape off any food that has dried on, but that's all I ever do.

> moving you towards that inky-black mirror of grandma's old pans

I really don't think that will happen. The reason your new cast iron pan doesn't have that shine is because they've changed how they make them.

Agree on hot oil. Not only non-stick, it also keeps meats moist and vegetables fresh (actually fried, not fry-boiled).

A few things I do:

Use wire mesh to clean, quickly, immediately after cooking.

Only use tap water to clean it. No detergents. This allows the pan to develop a literal taste of its own after a few months or years.

Heat the pan after cleaning, evaporating all water.

Yes on these 3, especially the 'no soap' rule.

For stuck-on food, I've had best luck with a coarse copper mesh pad (e.g. Chore Boy), which I use lightly, and only to remove the gunk.

In the past, I'd also used coarse salt as an abrasive, but I like the copper wool better.

I also heat the pan to dry it off. As to the comment about this promoting rust: if you have a well-seasoned pan, you don't have any wet metal; you have a wet seasoned pan. You could just as easily dry it with a dish towel, but this tends to get your dish towel dirty.

> Heat the pan after cleaning, evaporating all water.

Don't do that. It causes rust.

Metal rusts MUCH faster when hot than when cold. If you have wet metal that you are worried will rust get it as cold as possible, and let it dry. Best place is in the fridge - it's cold, plus low humidity helps.

A fridge is not necessary for cast iron, but don't heat it when wet.

How is heating it up for 2 minutes to dry it off going to cause rust compared to the 20 minutes you spent cooking with liquid in the pan?

Much more oxygen as it dries. You are not supposed to boil water with cast iron, you need oil when cooking which protects it from air.

The point is don't warm it to dry thinking it will rust less since it's wet for less time. Just let it dry in regular air.

I suppose that might be true, but have you actually done the math here?

If it dries say 50 times faster, does iron rust more than 50 times faster at 400F than at 70?

I have no way of knowing either way, but I've got a cast iron pan that belonged to my great grandmother and I remember my grandmother heating it to dry it off. My mom did the same with it, and now I've done the same--no rust.

I didn't do math. I did an experiment.

I took two identical pieces of metal. Dried one in a warm stove the other on a table.

The one on a table had no visible rust. The one in a stove was completely orange.

I don't doubt that warm metal rusts faster, just how much faster.

There's a pretty big difference between drying something in a warm stove vs applying a direct flame to it on the stove top.

It takes just a few minutes to get the skillet hot enough where the water pretty much instantly evaporates. I'd imagine putting it in a warm stove took much longer to completely dry it.

Direct flame would be even worse. It will rust much faster than it will evaporate.

Reaction speed doubles for every 10 degrees F, but evaporation doesn't.

Reaction speed doubles for every 10 degrees F.

That can't possibly be correct, or at least it's only correct over part of the range.

If a pan rusts at a given rate at 70F, it would rust at 2^33 times that at 400F--those numbers just don't work at all.

Also once the pan heats past the boiling point of water, there is a huge decrease in drying time.

If my cast iron can rust from two minutes on the stove, I need to stop cooking wet foods in it. It has yet to be a problem, though.

Of course. But that isn't what I said.

What I said was that if you are heating the iron in order to speed up evaporation to avoid rust, you are being counter productive. You will avoid more rust (if any would be formed in the fist place), by just letting it air dry.

I don't know what you said, then. People are saying we put our cast iron on the burner for a couple minutes to dry it off and you're saying the direct flame will cause it to rust.

In my house, we stove-dry pans constantly, precisely to prevent rust, and we never get any. It's not intentionally an "experiment", but it's enough to make me think there's an issue with your methodology.

You probably would not get rust anyway, so stove drying isn't hurting anything much.

But it's certainly not helping.

The methodology was not complicated: I washed some porous/rough metal under the faucet, dried it with a paper towel, then put one piece in the oven at 170F, one on the table.

170 is below the boiling point of water, it may speed up evaporation but it won't boil off.

300-400 (what you'd get from the stove top) is above the boiling point, so the water rapidly boils off.

These 2 things aren't comparable.

Maybe iron will rust faster when hot, but I don't think heating it to dry it is an issue -- I do that fairly often, and haven't had a problem.

Here's a counter example: There are many tons of metal in hot desert climates that have a small amount of rust on them, but nothing like the kind of rust from a cold wet climate. There may be complications from cooking, but, and this is without giving it much thought, I'd say that water is a much larger factor than heat.

> in hot desert climates

You still need water.

My understanding about the "grandmas old pans" comment is that new pans are cast, i believe using sand?, in a way that leaves the "pebbled" texture. It's unfortunate, the smooth cast is certainly better, but I believe it doesn't have as much effect as you might think.

I've got two of them that I bought about 15 years ago (Lodge brand) -- they both had that roughness to them. One I use daily (the round one), the square one not that often. Looking at the round one now, and it is perfectly smooth, just like grandma's. So it can be done, it just takes a bit of time.

Yeah, they've definitely started out closer to smooth than ours. As you say, I don't know if mirror smoothness is terribly important, but it might let you get away with a bit less oil.

If you want your pan smoother, you can always sand it smoother. Will need to re-season it afterwards, though.

As I understand it most of the old pans were sand cast too, but they then polished them before selling. Modern manufacturers skip the polishing step. You could always sand it down yourself as abakker detailed.

Do you consider oven-seasoning to still be important?

It's nice in that it might let you get away with less oil day-to-day. My best answer is that you can get away with skipping oven-seasoning if you follow the daily practice, but not vice-versa.

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