the science of cast iron

13 May.,2024

 

the science of cast iron

It didn’t take much Googling to see that just about every food blogger out there has a post on cast iron, how to clean it, how to season it, etc. It seems borderline obligatory, so for fear of being left behind, I’m joining the swaddled safety of the herd. Today at DFK we talk about cast iron, how to clean it, how to season it, etc.!

View Details

Joking aside, there really is a hell of a lot of information out there on cast iron, so if it’s a topic you’re keen on, a little searching will get you a lot of material. That’s what I did, and over the last days and weeks I’ve read damn near all of the how tos on cast iron, cross-referenced with my own notes and experience on the subject, and fallen down a deep rabbit hole of chemistry in the process. Some of the info I found is good – ironically a lot of it literally copied and pasted from one source to another – but a lot of it is highly questionable or outright wrong. My post today is a sifting of all of the good stuff and none of the garbage.

the pros and cons of cast iron

pros

Cast iron is extremely durable. It’s not unusual to have one (properly cared for) that lasts generations. Even if you find a beat up pan, there’s plenty of life under it if you know the tricks to save it.

In general, cast iron is very affordable. I have always trusted in Lodge brand pans (Lodge if you’re out there, feel free to now give me cast iron goodies for life. I won’t mind.) and you can find all sorts of shapes and sizes at a good price.

As a metal, cast iron has exceptional heat retention and heat capacity. This means it gets really hot and stays hot. The ability to achieve high, sustained heat makes it the best metal to use for searing proteins.

Cast iron can be seasoned to create a natural, durable, non-stick surface. Much more on that in a min.

It’s dope af. While I don’t think this is a technical point, there’s just something cool about a well-worn, well cared for cast iron skillet. Call me sentimental.

cons

Cast iron is a poor conductor of heat. This means it takes a long time to heat up (thanks in part to its density), and doesn’t heat up evenly. When using cast iron, make sure the flame or heat source is large enough to cover as much of the pan as possible, so heat is evenly applied. A large skillet on a small burner will absolutely create a hot spot where that flame is in direct contact with the pan.

They take more than average care and maintenance. To be sure, nothing about caring for a cast iron pan is difficult, but it’s admittedly more work than simply rinsing and drying. Personally I think the simple care is more than worth it for the value of a nicely seasoned pan, but the lazier cooks of the world may think of this as a deal breaker.

why you should season your pan (and a few cast iron myths)

Food sticking to a pan during cooking is really simple; molecules of the food bond to the surface of the cooking vessel (protein sticking to metal being the most prone-to-sticking combination). That’s it. Although your metal cooking pan or glass dish may look and feel smooth, at a microscopic level they are at best porous like a sponge or at worst, a craggy landscape with lots of opportunities for molecular bonding.

Seasoning is the process of treating your iron pan so that it develops non-stick properties (which also helps preserve the pan itself). Oil is added to the cast iron in very thin layers, which fill the cracks and crevices of the pan’s surface. The oil is exposed to high heat, which breaks the oil molecules down causing it to polymerize, firmly bonding to the cast iron and effectively becoming part of the metal.

The new surface of the pan is smoothed, since the oil filled in the rough surface, and just as importantly becomes hydrophobic or water-repelling (oil not liking water and all). Additionally, the high heat of the process causes the oil to carbonize, adding single-bonded carbon to the matrix of bonded oil. These properties create the non-stick surface of a good cast iron piece.

Once you have a seasoned pan, it is perfectly ok to:

  1. Use soap and water on your pan to clean it. This will not remove the seasoning. Just make sure to use regular dish soap, and dry the pan thoroughly immediately after washing.
  2. Use metal utensils in the pan. Mild use of metal utensils (like a whisk or spatula) will not remove the seasoning of your pan and will in fact gently abrade the pan’s surface making it less prone to food sticking.

You should avoid:

  1. Using abrasive cleaners or cleaning products on your pan. Stick to regular dish soap and a sponge. Avoid using steel wool or similarly rough cleaning pads.
  2. Highly acidic foods. The acid in these foods can break down the molecular bonds of your seasoned pan.

how to season your pan

what oil to use

First of all, when you purchase a cast iron pan that claims to be pre-seasoned, this almost always means it’s been treated to avoid rusting, not to be non-stick. Seasoning your brand new pan is the best time to do so since it’s as clean as it’s gonna get. If you have an old pan that happens to be badly damaged and/or rusted, there is a way to save it, and I’ve outlined that after this section.

What kind of oil to use in cast iron seasoning always seems to be of some controversy. I can tell you from personal experience and scientific research that hands down the best oil to use is 100% pure flaxseed oil. Flaxseed oil is very high in a specific fatty acid within the omega-3 family that breaks down (polymerizes) readily and effectively. Getting pure flaxseed oil will ensure no other chemical additives interfere with the process.

Yes, you can use other oils like canola, but they aren’t going to do nearly as good a job as flaxseed. Yes, flaxseed is expensive, but you’ll be using very small quantities and a single small bottle will last you ages. Any oil you choose to use should be as pure as possible and unsaturated, and preferably high in ALA/Omega-3 fatty acid.

seasoning method

Step 1 – Preheat your pan in an oven at 200F/93C to dry it of any surface moisture and open the pores of the iron.

Step 2 – With a paper towel, apply a very thin layer of oil to the entire cooking surface of the pan. A thick application of oil will cause it to flake off at the end of the process, so there are no shortcuts here.

Step 3 – Once you have applied the oil, remove as much as possible with a second paper towel. The pan will appear to have no oil in it at all, but it’s there.

Step 4 – Place the pan upside down in the cold oven. No drip pan is needed beneath it.

Step 5 – Turn your oven to between 400-500F/204-260C, allowing the pan to heat up with the oven. Once the oven reaches temperature, “bake” the cast iron for 1hr. The oven temp. must be above 375F/190C in order to break down the oil and allow polymerization. Yes, there will be some smoke created from the process, so prepare accordingly.

Step 6 – Turn off the oven and let the pan cool inside it, about 2 hours.

Step 7 – Repeat this process 6-8 times to develop a thorough, hard seasoning.

If the surface of your pan becomes sticky after any cycle of the seasoning process, it is because non-polymerized oil has been left on the pan and that occurs for one of only a few reasons:

  1. Too much oil applied to the pan.
  2. Oven set at too low a temp.
  3. Not enough time spent “baking”.

working with a damaged pan

Much of this information here came from a great post on the subject by a lady named Sheryl Canter. She really got into the topic of cast iron, and my thanks to her for passing on her experience. I have used her method for stripping down a cast iron pan and can attest to the process.

Please note: This method calls for the use of oven cleaner. Oven cleaner is real sh*t, and extremely toxic/caustic. Follow all instructions carefully, make sure you follow all safety precautions thoroughly, and take the use of the product very seriously.

Step 1 – Using oven cleaner (and all necessary protective gear – non-corrosive gloves, goggles, ventilated mask, etc.) coat your pan and leave it to sit for 24hrs. Once again – make sure it is in a well ventilated area and appropriately covered/stored to avoid contact with anyone or anything that may be harmed by it.

Depending on the level of residue on the pan, it may need 1 or 2 treatments of the cleaner. At the end of this step there should be no visible residue still on the pan after a rinsing and thorough scrubbing. The pan will be rusted, which is normal.

Step 2 – Submerge the pan in a solution of equal parts of distilled white vinegar and water, which will help to remove the rust created by the oven cleaner. Let the pan sit in the solution for several hours – usually between 10-15. Change the solution if necessary (once it becomes cloudy with rust), until you see little to no rust rising to the surface of the solution. Do not let the pan sit in the solution for more than 24hrs. or it may be ruined permanently.

The vinegar will counteract the lye in the oven cleaner, and help to remove the rust that was created, but at the same time the stripped cast iron is still susceptible to rusting, which will happen in the solution itself. Therefore you must monitor the pan in the solution to keep it in long enough to remove the majority of the rust caused by the oven cleaner, but not so long that the solution itself damages the pan.

Step 3 – This step must be done in quick succession, so have everything ready prior to beginning. Preheat your oven to 200F/93C.

Remove the pan from the vinegar solution and immediately wash it with sodium carbonate, also known as washing soda. This is the base that will neutralize the acid of the vinegar to prevent further rusting from occurring on the now naked pan.

Dry the pan thoroughly with paper towels and place it in the oven to further dry, about an hour.

Step 4 – Remove the pan from the oven and cover it entirely in a thin coat of flaxseed oil, using paper towels to simultaneously apply the oil and remove any excess rust. The oil will in effect clean any residual rust off of the pan and provide a protective coating.

Your pan is now ready to be properly seasoned and live anew!

For those of you new to cast iron, I hope this encourages you to go out and get a pan of your own. It really is an excellent (and in my opinion, indispensable) piece of kitchen equipment. For anyone who already owns cast iron, I hope this clears up a bit of confusion and myth surrounding how to care for it. With just a little effort and know-how you can own a pan your entire life, to pass on to the next generation of cooks and bakers!

Cheers – Chef Scott

 

 

 

 

Cast Iron Cooking: Tips, Benefits, Maintenance, and More

Cast iron cookware often evokes images of olden days and campfire cookouts, yet the classic culinary tool remains just as popular today as it ever was.

There’s a good reason why cast iron cookware has been around for so many years — it’s incredibly durable and long lasting.

If you’ve never used cast iron before, you may have heard intimidating horror stories about how hard it is to use, clean, and store.

But once you know the basic principles of cooking with cast iron, there’s a good chance you’ll find it just as easy to use and care for as many other types of kitchen equipment.

This article presents a general overview of cast iron cookware, its benefits, tips to get started using it, and more.

Share on Pinterest

Harald Walker/Stocksy United

What are the benefits of using cast iron cookware?

You will get efficient and thoughtful service from siao.

One of the main reasons cast iron has been held in high regard for so many years is that it’s nearly indestructible.

In fact, with a bit of cleaning and care, even cast iron cookware that’s been neglected and left to rust can often be restored to a condition almost like new.

What’s more, cast iron that’s been properly seasoned develops its own nonstick surface.

The best part is, unlike traditional nonstick pans made with Teflon or ceramic coatings, the nonstick surface on cast iron can be reapplied over and over again with a process known as “seasoning.”

The natural nonstick surface and sturdy nature may be cast iron’s most notable benefits, but the perks of the cookware don’t stop there. Some other notable benefits of cooking with cast iron include:

  • Holds heat well. Once cast iron has warmed up, it stays warm which helps keep food hot. But you should also know this means it takes a while for cast iron to fully heat up and fully cool down.
  • Works well with many heat sources. Cast iron can be used on any type of stovetop (gas, electric, or induction). It can also be used over an open flame like a campfire or placed directly into the oven as a baking dish would be.
  • Easy to clean. Once you know the fundamentals of cleaning cast iron, it’s no more difficult to clean than other types of cookware. Plus, its natural nonstick surface might even make it easier to clean than glass or aluminum.
  • Affordable. Cast iron cookware is often sold at affordable prices and since it lasts nearly forever, you can view it as a one-time investment. It’s usually easy to find cast iron at thrift stores and second-hand shops too.
  • Comes in many shapes and sizes. Cast iron skillets are probably the most popular form of this cookware, but cast iron is also used to make pots, griddles, cake pans, pizza sheets, and more.
  • Can be used for cooking and serving. Many people find cast iron cookware aesthetically pleasing and it can make a nice addition to any table setting. In fact, many restaurants even use mini cast-iron skillets as serving dishes.

Does cooking in cast iron have health benefits?

You may have heard that cooking with cast iron is a natural way to add more iron to your diet.

It’s in fact true that cooking with cast iron might add some iron to your meals, but exactly how much depends on a number of factors like what you’re cooking, how long it’s in the pan, and how well your cast iron is seasoned (1, 2).

If you’re looking to treat a condition like iron deficiency anemia by cooking with cast iron, you should know that the research on this topic is still very limited, and the amount of iron added to your diet by cooking with cast iron is likely negligible.

Using cast iron to get more iron in your diet may be most effective when used alongside other therapies like supplements and dietary changes (3).

SUMMARY

Cast iron cookware is long lasting and with proper care it maintains its own natural nonstick coating. It’s also versatile, affordable, and readily available in all kinds of shapes and sizes.

Tips for cooking with cast iron

Cast iron cookware is suitable for many types of cooking but especially:

  • browning
  • searing
  • sautéing
  • baking
  • braising
  • roasting
  • frying

Some foods commonly prepared with cast ironware are:

  • meats
  • eggs
  • vegetables
  • meat substitutes like tofu
  • bread
  • baked goods
  • griddle cakes like pancakes or fritters

Cast iron works wonders for many foods, but there are a few cases where you might want to avoid cast iron cookware, such as when you’re boiling water or letting something simmer.

The reason is that your food may absorb more iron flavor than you’d like if it’s cooked in cast iron for an extended period of time.

Further, acidic foods like tomatoes, lemon juice, wine, and vinegar are likely to absorb the iron flavors of cast iron, which may be undesirable at times. They’re also harsh on cast iron cookware and might remove some of your pan’s natural nonstick coating.

SUMMARY

Cast iron works best for browning, sautéing, baking, and frying but should be avoiding when boiling and simmering. Meats, vegetables, and baked goods work really well in cast iron but acidic foods like tomatoes should be limited.

How to maintain a cast iron

There are four fundamental steps to caring for cast iron cookware:

  1. Season it properly.
  2. Clean it regularly.
  3. Store it safely.
  4. Re-season it as needed.

Compared to tossing a pan in the dishwasher, caring for cast iron may seem like a lot of extra work at first glance.

But once you’ve run through the process a couple of times, you might decide the extra few minutes you spend caring for your cast iron is worth having a sturdy nonstick piece of cookware that can be used over and over again.

Here is an overview of each step in caring for cast iron cookware:

Season it properly

“Seasoning” cast iron protects the cookware from rust and creates a natural non-stick surface. It’s arguably the most important step to caring for cast iron.

Seasoning works by coating cast iron in liquid fat-like oil and heating it up past the smoke point until the fat polymerizes. When fat polymerizes, it turns from liquid into a slick, hard solid that the porous iron cookware absorbs creating a nonstick surface.

Virtually any type of cooking oil can be used to season cast iron but keep in mind that oils with strong flavors, like avocado or sesame seed oil, may subsequently flavor your cookware and the foods you prepare in it.

Many people like to use a basic vegetable or canola oil because they’re affordable, easy to find, and have a neutral flavor profile.

Whichever oil you end up using, be sure to heat your pan past the oil’s smoke point so polymerization occurs.

To season cast iron cookware:

  1. Starting with a clean piece of cookware, rub a light coat of oil (too much oil will create a sticky pan) over the entire thing including the top and bottom, inside and outside, and any handles.
  2. Place the piece of cookware in a preheated oven between 450°F–500°F (232°C–260°C) for approximately one hour. It’s usually a good idea to put a baking pan on a lower rack of the oven to catch any oil that might drop off.

Clean it regularly

Cleaning cast iron after each use is ideal to prevent rust and maintain a nonstick coating. Because cast iron tends to absorb flavors easily, it also helps ensure that the next dish you make won’t taste like the one prior.

Some people choose to completely avoid using soaps and abrasive sponges to clean their cast iron out of fear it will damage the nonstick seasoning. For these reasons, it’s also usually best to wash cast iron by hand instead of using a high-powered dishwasher.

In actuality, a little scrubbing and a small bit of soap probably won’t do much harm, but you definitely won’t want to overdo it or you’ll likely end up needing to re-season your cast iron quite often.

An easier option might be to use a bit of salt which provides just enough abrasion to remove any residue and leftovers without damaging the nonstick layer.

Or you can try a tool called a chain mail that’s made of linked rings of stainless steel or titanium. They’re also great for cleaning cast iron yet leaving the nonstick layer unscathed.

Store it safely

To prevent rusting, before you store your cast iron you want to be absolutely certain you’ve removed all food residue from the pan and dried it completely.

After you’ve washed cast iron, you can dry it with a towel, by heating it in the oven, or even on the stovetop.

Re-season it as needed

No matter how well you maintain your cast iron, it will need to be re-seasoned from time to time.

If you choose to dry your cast iron with heat such as in the oven or on the stovetop, it also makes for a good opportunity to add a thin layer of oil and heat the pan up to the oil’s smoke point to maintain the nonstick coating.

If you start to see rust or notice that your pan is turning lighter in color, it’s a good sign that it’s time to re-season.

SUMMARY

To care for any type of cast iron: (1) season it properly (2) clean it regularly (3) store it safely (4) re-season it as needed.

The bottom line

Investing in a set of cast iron could mean having a durable set of nonstick cookware that lasts nearly forever.

Learning how to properly care for it is critical to maintaining the lifespan, but once you’re comfortable with the process it’s fairly easy to incorporate into your usual kitchen cleaning routines.

Thankfully, cast iron is relatively affordable and readily available at retail kitchen stores.

Or if you want to test out cast iron yourself before buying a new piece, check your local second-hand shop and try re-seasoning an old piece to make it like new again.

Try this today

Just one thing: Are you just getting started with cast iron cooking and wondering what to make first? Here are a few of our favorite recipes to try!

Was this helpful?

For more Cast Iron Cookwareinformation, please contact us. We will provide professional answers.