Chemistry of Cast-Iron Seasoning (2010) | Hacker News Reader

Chemistry of Cast-Iron Seasoning (2010)

sherylcanter.com

81 pointsTomte77 comments

Fascinating, but I'm not going to do it. I respect the people who take this kind of care of their equipment, but I have an alternative that works quite well for me: cook your food in an adequate amount of fat. If it sticks, you don't have enough fat in the pan. When you're done, wipe the pan clean. If food is stuck hard, scrape it out, using steel wool if necessary. Cast iron is amazingly robust and develops a decent season on its own with daily use. As long as you're not super-uptight about maintaining a polymer layer on top of it, you basically can't do anything to hurt a cast iron skillet. And I'm far too busy to spend a whole day thermal-cycling a chunk of metal.

Cast iron is also really heavy. I have two cast iron skillets and I only use them when my non-sticks and magnalite are already dirty.

Consider it strength training. For my part I don't trust non-stick pans; the coating flakes off into your food over time and who knows what happens to it in your body.

I think I'm going to end up going stainless. Hits the sweet spot in terms of durability, safety, convenience, and weight.

Although it seems like the ideal on paper, stainless heats unevenly and sticks. IMO cast iron is ideal, albeit heavy.

Most of the stovetop cooking I do is just heating up rice or noodle dishes that I make in big batches. Those I make with big cast iron dutch ovens. The enameled ones are awesome.

For that stainless is a good choice. I usually use cast iron to fry, or toast things on the stove top, so sticking and even heat are important. Stainless is useful in a bunch of other areas though. Basically all my cookware is white stainless, or cast iron, not a fan of synthetic coatings.

Have you thought about copper?

Can be more expensive than stainless and has the same issues with acidic sauces (ie, tomato based), but it heats up really well, and you can get it pretty thick for a little more heft.

Plus, it looks nice (especially if you can find some antique French pieces).

Stainless 3-ply with Aluminum in the middle is perfect for even heating and indestructibility. It's not quite as non-stick as cast iron though.

Stainless is nice, it only loses on thermal mass and non-stickness. But if what you want is food, not perfection, it doesn't narrow your options much, and is much easier to maintain.

The weight is an important feature: Cast iron has higher heat capacity and won't lose heat as fast when food is added. This is why cast-iron should be your go-to pan when searing a steak, for example.

The downside is that they take longer to heat, of course, so other pans can be more suitable for some cooking tasks.

Cast iron also has an excellent use case in which you can do any searing and such on the stove, then transfer it directly to an oven to finish. This is the secret to making S-tier steak.

Reverse sear is even better; by going oven-first you dry out the surface and get a better sear.

I look forward to trying this out!

> Cast iron also has an excellent use case in which you can do any searing and such on the stove, then transfer it directly to an oven to finish.

To be fair, lost of pans (not non-stick) can be used this way, it's not a unique feature of cast iron.

This is true, but it's also true of a lot of other non-cast iron cookware. Lots of pans are oven-proof.

It also heats very evenly, eliminating hot and cold spots.

Cast iron is not ideal for even heating, it's a myth.

http://www.cookingissues.com/2010/02/16/heavy-metal-the-scie...

Cast iron has low thermal conductivity. You can have oil smoking hot on a cast iron pan, but you can still hold the handle.

Buy old pans at yard sales if you can find them. They are much lighter and much more refined/polished compared to the new mass produced pans.

There are a number of cast iron pans out there that are lighter but you'll need to pay more for them and look for them specifically. Try searching for Field or Stargazer pans.

Also some very interesting-looking Iwachu pans from Japan[1], though I haven't tried one yet...

1: http://www.core77.com/posts/39670/Iwachu-Skillets-Effortless...

“Really heavy” is generally a positive trait in cookware.

Which makes it ideal for induction ranges, I will say. It's also one of the reasons it's still possible to buy a secondhand cast-iron pot or pan that's 100+ years old.

Have you considered carbon steel skillets? They're not as worry free and have less heat retention than cast iron, but they're also much lighter and can be seasoned to a non-stick finish.

My skillets almost never leave the stovetop. Other than soups and sauces, everything I do on the stovetop, I do in cast iron anyway, and I use one every morning for my eggs. I try to rotate which one I fry eggs in because I find that eggs improve the condition of the pan.

You should try a carbon steel skillet: https://www.youtube.com/watch?v=-suTmUX4Vbk&t=

Yeah I agree with this. It takes a long time for a piece of cookware to get well-seasoned in this way, but it works fine. Something not noted in the article is that once the oil is polymerized, it is not going to come off with dish detergent, so all the advice you hear to never use dish soap on seasoned cast-iron is erroneous. If there's non-polymerized oil on the pan after you're done cooking, you _want_ that oil off of the surface, otherwise you end up with a layer of congealed fat, not a good seasoning. When my wife and I bought our current house, it came with a stove with a cast-iron griddle, and the previous owners had taken the "never wash it" approach and it was nasty. I stripped it down to the metal and started cooking on it (after doing a quick initial season where I coated it with oil and heated it past its smoke point). Two years later, it's developed a nice seasoning, even though I wash it with detergent after every use.

Once your pan is well seasoned, do you worry about acidic food (tomato, citrus) damaging the seasoning?

I used to, but after trying it I no longer worry about it. Even boiling tomato sauce has no noticeable impact on the seasoning as far as I can tell.

We made a tomato sauce in a cast iron pan. Once. It was god-awful. It was like eating iron filings. You couldn't taste anything else.

Sounds like you used a rusty pan.

Very new, "pre-seasoned" plus oven-seasoned once.

That was probably the issue. Pre-seasoning is mostly bullshit. The best seasoning is just using the thing daily for a few weeks/months IMHO. Very new pans have not had the time to build up a good solid coating.

New? Y'all don't have antique stores or flea markets where you live?

Not exactly sure what you did wrong, but you did something wrong.

You probably should have polished it with a metal scouring pad first.

Same here. Although for scraping I use a plastic scraper instead of steel wool. Once the pan is clean I put some oil in it and heat it up for a while. That's all and works really well.

Lodge makes a good plastic scraper with a different radius on each corner, but really any hard piece of plastic will work.

I use a stiff bristle brush without soap. I just run hot water into the pan and then go to work, scrubbing the bottom and the sides of the pan until clean. I towel dry the pan and then set it on the stove top overnite before putting it away. Two sizes of pan and a dutch oven all receive the same treatment. I rarely use my expensive alloy pots and pans any more.

> steel wool

My favorite tool for scraping stuck food particles is a one of those stainless steel ring chain mail things. They wash nicely in a dishwasher and do a good job of homogeneously scraping the surface of the pan.

Frying more bacon is also a good technique. My cast-iron gets a smooth, almost glassy finish on it whenever I go through one of my heavy bacon-frying phases.

Plus, more bacon!

I was going to make this point in a post, but saw that you had already done so.

Using the pan repeatedly as a griddle will result in a superbly seasoned pan that does not need much attention or cleaning.

Once in a while if the pan is used for something too gooey or saucy, or if it gets put through the dishwasher, I simply do a quick seasoning as follows, before resuming its typical use as a griddle:

1) Rinse or wash the pan, use a scouring pad or steel wool if there are any burnt bits of food stuck to the surface.

2) Wipe cooking surface of the pan with a thin layer of olive or vegetable oil. Wipe it in with a paper towel and do not leave any excess in the pan.

3) Heat the pan over a burner at medium heat, so that it gradually warms up, then becomes hot enough to produce a small bit of smoke.

4) Pour in a bit more (room temperature) oil, and once again wipe/rub this around the cooking surface of the pan.

5) Let the pan heat for another minute or two until it is once again at the smoke point, then turn off the burner.

This quick process takes about 5 minutes. It thoroughly dries the pan after washing, which prevents rust, and it gives it enough initial seasoning to bootstrap the seasoning process for subsequent uses of the pan as a griddle.

> you basically can't do anything to hurt a cast iron skillet

The only ways I could think of involve self-defense in a home invasion scenario.

I think most of those scenarios involve a person getting hurt and a cast iron skillet walking away unharmed.

We use our cast iron pan almost daily and I fully agree the key is using enough fat. Generally after scraping out any solids I give it a quick rinse with soap and water, place it back on the burner at a low heat for a minute to drive off any remaining water. Every few days I might give it a light wiping with coconut oil.

We put olive oil on the pan and then wipe it with a paper towel so that it is only a very thin layer. I then use a tablespoon of butter to cook scrambled eggs. If the pan is the right temperature it is usually super easy to clean.

I normally do like many people here, which is just wipe on a thin coat of oil and burn it off on the stove-top (covered in aluminum foil to reduce oily residue on kitchen surfaces) when I think the seasoning needs an extra touchup beyond what it gets from cooking. Years ago I tried the oven trick, but as you say it's just not worth the bother. Plus, it can really dirty your oven and your whole kitchen.

But last year I had the idea to season the pan on my Weber coal grill.[1] And it worked extremely well. On the grill you can season both sides and the handle just like in the oven, but without worrying about the sticky residue it creates everywhere else. You can get the pan much hotter than in the oven, and more evenly than on the stove. My IR thermometer measured the my pan at something over 700 degrees fahrenheit on the grill, which was about as high as I wanted to go.

My pan was purchased unseasoned and the seasoning I managed before trying the grill was spotty, uneven, and prone to flaking. After about 15 to 20 minutes (or maybe 30? I don't remember precisely) on the grill the seasoning was perfect on every surface--as shiny as fresh oil, but completely dry. I applied one really good coat of oil, enough as I could manage without it pooling and creating runs, and wiping off any excess that pooled as the pan heated. The primary reason you normally season with thin coats of oil is, I think, to ensure an even, consistent surface. But on the grill you can wipe off any excess as it pools, so you can apply a much thicker coat in one shot rather than bake-on multiple thin coats.

For no good reason I stupidly tried to season the same pan on the grill a second time several weeks later. The second time I was lazier and less cautious and managed to burn off some of the existing seasoning, as well as letting too much oil pool and run in some spots, which became prone to flaking. But in neither case was the seasoning ruined all the way through to the iron. That's the danger of doing it on the grill, I guess. At 700 degrees you don't want to keep the pan in there too long as it'll ruin the seasoning--pools and runs will quickly harden, leaving an uneven surface that even wooden utensils can end up lifting, and hot spots can get much hotter than you'd want. I think at somewhere around 900 degrees seasoning will just completely burn-off in short order.

The only discussion about seasoning pans over an open fire I found online involved someone recounting (himself or someone else) seasoning pans over a camp fire. IIRC the advice I read there was to be careful as at too high a temperature not only will you destroy the seasoning, but you can damage the cast iron itself, either cracking it or changing its thermal properties. But with an IR thermometer, a spray bottle of water, and some coals you can get an amazing seasoning in one shot in under 30 minutes, and then grill lunch.

[1] It came to me sometime after I got the idea to fry chicken on the grill. I like making pan-fried chicken in my cast iron pan, but my wife hates the mess. (I hate the mess too, I just like the fried chicken more.) Frying on the grill works pretty well, but controlling temperature is difficult, especially because it's not easy picking up a large cast iron pan from a hot grill to reposition hot spots or to be able to spray some water over the coals. (Or maybe I'm just a wimp.) I'm still experimenting with technique, but I've yet to have an out-and-out fail.

And, yes, I keep a large ABC-rated fire extinguisher nearby, as well as some small foam extinguishers for stove-top fires so I have options and don't hesitate.

Nice to see someone explaining drying oils, a discussion usually buried in woodworking forums. That said, in addition to flaxseed oil there a few other drying oils that can be food safe, depending on the additives, like safflower oil, walnut oil, soybean oil and tung oil. In their raw forms those oils are edible, but if they contain a metallic dryer catalyst to accelerate the drying, they're not food safe. I've purchased raw linseed (aka flaxseed) oil in a hardware store in fairly large quanity, labelled as being "safe for farm animals". On the other hand the "boiled linseed oil" sold in the same store contains the chemical dryer and has a label indicating it's toxic. The boiled variety is better as a wood finish when you don't care about it being food grade because it dries much, much faster. For wooden bowls, etc. the raw linseed oil is preferable as a food-safe finish but it takes a very long time (weeks) to dry unless aided by heat / sun.

Good timing on this post, I was researching this last night after one of our wooden bowls was placed in the dishwasher by mistake.

There's conflicting information out there about flax/linseed oil - All state that the boiled variety is not food safe, but advice on raw linseed oil is quite divided. Some advice says it's fine, some not. The bottle of raw I currently own says not to ingest, so I'm taking it to be not food safe :)

One of the commonly suggested alternatives is to use mineral oil, or a combination of beeswax and mineral oil. Knowing that mineral oil is a product of crude oil refining really makes me uneasy, but at the same time I know that's an appeal to nature fallacy.

Walnut oil is sounding like an expensive but worthwhile third option.

Mineral oil is literally sold as a laxative. It does this mechanically, ie by being indigestible and lubricating things along. That suggests that it’s pretty safe to ingest.

Perfectly safe to ingest. I've done it once, because, well - you know.

Taste? Literally tasteless. But it has the texture of plain oil; I can't really describe it, but you have to have a very good gag reflex control to get it down. Then you have in your mouth this "oiled" feel.

Not pleasant, but I was desperate and in pain, and it was all I had available at the time.

Mineral oil is also used medically as a laxative; you put a few spoonfuls in a glass of juice and drink it. So, pretty safe to use as a wood conditioner but its not a drying oil so needs to be re-applied from time to time. It's used a lot on wood cutting boards, which take a lot of abuse and need regular re-application of a flowing finish that won't build up in hard layers.

Wax can be used over most wood finishes to to give it added lustre but also needs to be re-applied to maintain it.

The advantage of a drying oil is that it gets absorbed deeply into the pores of the wood grain and dries to a plastic-like hardness. Because the unpolymerized oil penetrates so deeply, the cured finish isn't just a hard layer weakly bonded to the wood surface which can flake off, but weaves itself into the grain and pores of the wood itself. It seems that most people who avoid linseed oil finish complain they don't like the smell when working with it.

Walnut oil can be dangerous for anyone who has peanut allergies, which might be one reason why its not so common.

Yes, look up the MSDS on anything like this -- BLO has Cobalt-Manganese salts.

I discovered this site years ago, when searching for information about how to season cast iron. I had a cast iron skillet I'd been using off and on for a few years at that point, but was still having trouble with food sticking, and so figured I'd made an error in seasoning the skillet initially.

I have to say, the techniques described in the article work well. I have a few skillets I seasoned using this technique, and using only a little more as cooking fat as I'd use in a teflon pan (1/2 Tbsp vs 1 tsp), I can cook eggs and not have to worry about them sticking to the pan. Many a delicious omelette has been made in my 8" lodge skillet after I seasoned it with this technique. The same was not true beforehand.

sevensor does correctly note that this can be a lot of work and take a whole day, but bmcusick also correctly points out that it doesn't have to. I seasoned the 8" Lodge skillet mentioned above over the course of a week, applying 1-2 layers in the evening while I was in the kitchen anyway to cook dinner or clean up. And after that week was up, I then had a cast iron skillet I could cook eggs in. Totally worth it.

I've been using this technique for years and highly recommend it. I've only had to re-season my main pan from scratch once in five years, after accidently forgetting about it on the back porch for a week (that's Florida humidity for you).

It's great. I've seen people warn you to not wash your cast iron with soap so as to not damage the seasoning, but I use soap without fear. I've heard from others they even put their cast iron in the dish washer, although I haven't tried that personally. This creates a base layer of seasoning that's REALLY hard to get off.

Maybe it sounds like a lot of work, but it really isn't as long as you're not in a rush to get it all done in one day. I'd add a layer of oil, run the oven while I gave the kids their bath, and turned it off after. Maybe 5 minutes of work per day over 3-4 days.

This isn't a "science-based" how-to, it's a "searched-about-science-on-google" how-to.

The whole blog is basically just a Facebook feed.

Nice to know somebody has (maybe?, yet again?) found the secret to seasoning cast iron pans. I'm beyond trying to use cast-iron cookware now, thankfully.

I threw out most of a second complete set of cast iron cookware. I kept a Dutch oven, fantasizing that I'll someday carry it afield for camping. But I probably won't.

Instead its heavy burden, like that of most cast iron cookware, will be passed to the unlucky fool who inherits it. I have no doubt that in whatever future time that occurs, there will be people posting articles like this anew on the internet, encouraging the use of one of the most cantankerous and frustrating iron-age technologies that ever existed.

Once upon a time I might have, as the article suggests, paid $17 for 50 cents' worth of flaxseed oil in order to perform yet another tedious failed organometallic chemistry experiment.

But instead I'll save my money for a new T-fal frying pan, which works flawlessly, perfectly, year in and year out, without seasoning and without a hitch. If Armageddon comes and there are no more T-fals, then I will cook with sticks and stones before I attempt cast iron cooking again.

Stainless is a good alternative to cast iron as long as it’s thick enough.

Cast iron has only one major advantage and that is due to its mass it holds a ton of heat which makes searing on it very easy.

This is important as the vast majority of thin and light cookware basically goes cold when you dump food on it regardless of how hot it was.

So cast iron allowed you to control the temperature well and cooking or searing food on low heat after a long pre heating period.

With good mass stainless steel cookware and a good induction cooker you can easily achieve the same results as a good cast iron even better as a good induction cooker would allow you much finer control over the temperature of your cooking surface.

Good stainless and induction cookware has a much more even distribution of heat than cast iron, as well.

http://www.cookingissues.com/2010/02/16/heavy-metal-the-scie...

Yes cast iron doesn’t really heats up that evenly it just hold a lot of heat.

The problem is that a lot of cookware these days is made super super thin as a cost saving measure and to provide fast heat transfer.

This means that you lose a lot of control as thin cookware overheats easily and has hot spots, especially on direct transfer electric or gas stoves.

I do still own a large cast iron skillet and use it to sear large chunks of meat but I actually polished the hell out of it with a few polishing heads on a drill.

For seasoning I used vegan lard/cooking fat which is made out of pretty high smoking point oils and it still holds up for 2+ years.

It took like almost a day to get it done with 8 layers of seasoning, if I’ll have to completely redo it I would likely just say fuck it.

> flaxseed oil is the only drying oil that’s edible.

Ahem. Oil painter materials nerd speaking up.

The other drying oils are walnut, safflower, and poppy. They are all edible. Although poppy is sometimes classed as semi-drying, along with sunflower, to be pedantic...

anyway. interesting writeup. :)

Maybe the results are better, but this seems like an overly elaborate technique to season a pan. It's a full day of heating/cooling/rubbing the pan to season it? F that. There is a whole lot of handwringing over "zomg free radicals cause cancer" in the article that's all about the nearly impervious coating on the pan. If the coating is getting into your food in nontrivial quantities you're doing something wrong.

I think I might try this over the next few weeks. No one says you have to do it all in one day. Do one layer a night before bed and it'll be seasoned in a week.

How can I find cast-iron re-seasoning services?

I have a cast iron pan that I love. It's heavy as fuck but it's just the one I like cooking with the most. I've taken pretty good care of it, but still the seasoned surface is pocked and scratched after years of service.

I'd like to have it reseasoned from scratch, blank-slate style. I've found many guides on how to do that, but honestly I don't want to have to deal with lye or electrolizing to remove the old stuff off. Nor do I want to spend a day/weekend baby-sitting the pan in the oven as I put 3-7 layers of seasoning on it.

Who could do this for me?

Do you have any local friends who have the space & time to deal with lye or electrolysis? They might be willing to do so in exchange for a few beers or maybe a steak cooked in said cast iron skillet.

Another thought that comes to mind: Check our your local hackerspace, if you're a member of one. There might be someone there who likes to nerd out about cooking equipment who would have fun re-seasoning a cast iron skillet from scratch.

I have no idea whether there are services for this. I'll just offer this, based on my experience-

1) Electrolyzing is overkill. Steel wool and elbow grease is fine. If you really want to go to town, get a steel whisker brush for your hand drill.

2) Don't try to re-season it all in one day or weekend. After dinner in the evening, before you start watching some Netflix or checking Twitter, rub a coat of oil on it and run the oven for an hour. Set a timer so you don't leave it on by accident. In the morning the pan will be cool and ready for the next coat. Maybe 2-3 minutes of work per day that's easy to fit into your schedule.

I used a wire brush cup on my angle grinder, very fast and no need to deal with lye or anything caustic.

If I read this correctly the second best option which is much more cost effective is canola oil? Also can someone find out from Lodge why they chose soybean oil? That would probably be informative. http://www.lodgemfg.com/use-and-care/what-is-seasoning

Saw an article about seasoning cast-iron. I was going to find the article I refer to for my pans - turns out it was this one. +1 would recommend. I did as other people have mentioned in the thread - coat it, put it in the oven around 9pm, turn off around 10:30 (preheating to 500 takes a long time), take out in the morning, repeat for the week. Easy peasy.

From the manufacturer:

"Lodge seasons all of its cookware with soy vegetable oil and nothing else. Any food-safe cooking oil/shortening will work for maintaining your cookware. We recommend vegetable oil or canola oil, like our Seasoning Spray."

If you can't get this consistently right, get a ceramic or vitrified iron pan. If you are not worried about the color getting dull, you can even safely put vitrified iron pans in the dishwasher.

Best Solution: Just get a non-stick ceramic pot and cook nothing but rice and beans. Season lightly with the tears produced from flavor boredom and possibly malnutrition ...

EDIT: Also student loan debt ...

Came for some chemistry, stayed for the obsessive perfectionism.

Lodge also makes a carbon steel skillet that I cannot recommend enough. In my opinion there is no noticeable difference in performance and a lot lighter. My favorite pan.

Does anyone know if this would work with a wok?

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