How do I know when I need to re-season a cast iron pan?

You get a new pan from the store, or an old, new-to-you pan from a family member, and the first thing you’re likely to do is spend some time re-seasoning. Fresh from the factory, or stale from neglect, obviously is a great time to put in the effort.

But what about the pans you already own and are using regularly? How do you know if they need some intensive cast iron care or even a full seasoning restart?

I was cooking a batch of buttermilk pancakes this morning and noticed a chip on my twenty inch grill, the same pan that had given me some trouble a couple months back (but in a different spot on the pan!) That blemish had likewise started as a small chip and I’d let it fester for a few months only to watch it grow from a dime-sized divot into a scar that rendered a quarter of the large pan basically useless.

Now this new pit has me pondering my pan options: to push through, spot-repair, or fully re-season?

So, how do you know when it’s time to start the re-seasoning process?

It’s Wearing Out

Seasoning is just layers and layers of carbon built up over time and effort. Maybe those layers are just getting old, or thinning out in various places. Maybe you’ve been cooking too many delicious tomato sauce-based recipes and the acid and lack of fresh oil is leaving those layers a bit lacklustre. Or maybe you’ve built up so many layers that the actual shape of your pan is starting to change. Seasoning does get old and wear out, and a once-amazing pan might just need a refresh.

It’s Chipping Off

Like my morning dilemma, sometimes you pull a pan from the shelf and either from rough use or being bumped in the cupboard, a bit of the seasoning has actually cracked and chipped away. This creates an unwelcome uneven surface and over time is simply going to get bigger and rougher and make your pan less useful. A full re-seasoning on a big chip or a chip in the main part of the pan is probably the best course, but try a spot re-seasoning first. Scrub the spot down with some steel wool or an abrasive sandpaper, then re-season like it’s a new pan. If that doesn’t work, strip the whole piece to bare metal and start fresh. Plus, you don’t want any of those stray seasoning chips mixed in with your morning hashbrowns.

It’s Rusting Up

The worst cast cast iron scenario is rust. Stored wet, or maybe having been through a long cold winter (accidentally, I swear) left inside the barbecue, rust damages the iron at a molecular level and loosens your seasoning. Also, it tastes awful with eggs. A full cleaning and do-over is probably the best way to get back on the right foot with a pan that’s got a case of rust.

Most of all, you’ll likely just know when you need to re-season. A well-seasoned pan is a great tool. A pan that needs some care and attention from years of use, wear and tear is just …less so.

How long does it take to season a cast iron pan?

Probably one of the most well-known bits of cast iron lore is that the more that you use your pan the better it will get.

This rule of thumb is referring to the seasoning, the thin, black layers of polymerized oil that have been converted to this state by heat and have adhered to the surface of the pan creating that famous non-stick state of cooking bliss.

Pre-seasoned pans from the factory are sold with a few layers of seasoning applied shortly after manufacture, and for many this is “good enough” to start cooking with your new pan even as you peel the labels off. But for others, a fully seasoned pan takes work, and adequate seasoning is a matter of opinion and personal evaluation. To them, no pan ever comes from the store with enough seasoning to be considered fully ready to cook on.

The most unhelpful advice I’ve ever read on seasoning basically says that a pan is fully seasoned when you know that it is fully seasoned.

What those folks are getting at is simply that it will feel like it cooks better. Or it will pass some kind of non-stick test. You’ll just know… y’know?

A test, you say? For example, some swear that a pan is only seasoned when it passes the egg test: crack an egg into the center of a hot pan, cook it to doneness, then slide it onto a plate… all of this without using a spatula or any other cooking tool. If it slides into the plate and leaves a clean pan behind: voila! Your pan is perfectly seasoned. If it sticks then get back to work: you’re not there yet.

But no, you insist, really how long does it take to season a cast iron pan?

In my experience, it takes however long it takes to build up five … ten … twenty solid layers of seasoning. You’ll just know… y’know?

That might take just one quiet afternoon with a hot oven, some oil and a bit of elbow grease.

Perhaps a full weekend out camping and cooking all your meals over a fire where the hot flames meld oil to iron will find your pan seasoned perfectly.

Sometimes a couple months of casual cooking at home is required as you notice week by week that your pan gets a little smoother and easier to use each time you fry.

Or occasionally it will take years of waking up early to prepare delicious Saturday breakfasts for your still-sleeping kids until you realize that your seasoning should be considered a family heirloom.

So maybe those folks with the unhelpful advice are right. A pan is fully seasoned when you know that it is fully seasoned. You’ll just know… y’know?

Can I use a self-cleaning oven to strip a cast iron pan?

The short answer is yes.

The more complex answer is … maybe.

A self-cleaning oven is the closest most of us have to a blast furnace inside of our homes. And as many people will tell you while there are multiple ways to strip old seasoning from cast iron, the high heat of an oven’s clean cycle might be the simplest.

My oven claims that on self-clean mode the temperature gets to nearly 900 degrees Farenheit (or about 480 degrees Celsius.) That’s hot. Hot enough to incinerate the seasoning off of any pan.

So what is cast iron seasoning anyhow that we can burn it off our pans, pans that we use over heat all the time?

Cast iron seasoning is a layer of polymerized oil.

Oil is a word we use to describe a vast variety of chemicals with complex molecular structures and specific physical properties. Cooking oils generally come from crop plants and we can eat them.

Polymerizing is a fancy way of saying that many smaller molecules can be chained together to form one massive molecule. Plastic, rubber, nylon are examples of polymers you might be familiar with already. Cast iron seasoning is also a type of polymer.

Cooking oil at the right temperature can be turned into a polymer onto many types of surfaces. We take advantage of this process to season cast iron cooking pans, covering them with lots of very large oil polymers that at the correct window of temperatures create a non-stick cooking surface. Simplistically, we are creating a kind of coating by linking uncountable small oil molecules together using heat.

This coating improves and strengthens with just enough heat, but as with many types of natural compounds if we use even more heat we can destroy it too. By design, because we like to have clean things, it incinerates at the same temperature of other charred food bits, grease, and cooking stains… or the temperature a self-cleaning oven.

So, yes, you can exploit the almost-blast furnace temperatures available in your kitchen to burn the polymerized oil layer from your cast iron pan and “clean” it bare in your self-cleaning oven. Almost 900 degrees Fahrenheit will reduce those polymerized oils to a fine ashy powder that you can wipe off with a damp cloth.

The maybe part of this answer is that high heat is unpredictable. Even some of the best cast iron is not made as uniformly as it may appear as you heft that heavy pan onto the fire. Pans are meant to be heated and then disperse that heat in a specific way (into food, into the air, etc.) So when you heat a pan in very hot in contained space, in a way it was not designed to be heated, there is a chance it could crack or warp.

I’ve personally stripped multiple pans by this method and never had a problem, but all of those pans were replaceable and inexpensive. If I was restoring something more valuable or an antique, I might not take the shortcut of a self-cleaning oven.

So again, can you use a self-cleaning oven to strip a cast iron pan… maybe. This method is fast and convenient (especially if you’re already cleaning your oven) and you can start fresh with a bare metal pan. This might be worth the maybe.

Cast Iron Care Checklist

Kinda surprising actually that I haven’t written on this topic yet, but here goes…

If you’ve been thinking about investing in a cast iron cookware collection, your new pans and griddles need a small collection of tools to live their best life with you.

As with many hobbies, there are expensive and cheap versions of available care accessories. Many companies will happily sell you branded tools, purpose-made implements, and specially crafted concoctions. Most of these items are important to care for your iron, but the pricy version of it is not. Cheap or free alternatives often exist. After all, cast iron cookware has been common for hundreds of years, but imported organic flaxseed oil probably has not.

Ten of the tools I keep handy to maintain my cast iron collection are:

Seasoning Oil – Personally, I lean heavily on canola oil for a post-cleanup wipe-down because we always have it in quantity and handy, but I also keep a bit of shortening or leftover bacon grease in the house for my purpose-seasoning efforts. There are numerous products on the market that are labeled as cast iron seasoning products (and I intend to buy some and try them) and many people online swear by flaxseed oil (but it is expensive). Whatever your oil of choice, this tool is a must for ongoing maintenance of your pans.

Heavy Duty Paper Towels – If I’m feeling flush, and I happen to be near a hardware store there is a brand of blue, commercial grade paper towels that are just about perfect for cast iron clean up. If I don’t have these around, plain old paper towels are a must for our supply closet.

Coarse Salt – The first time I tried it I was amazed by how much basic post-cooking cast iron cleanup could be accomplished with a quarter cup of water and a tablespoon of coarse salt. A few minutes of simple soaking usually means that with only salt and elbow grease I can clean up almost any pan. For anyone new to cast iron who is skeptical about the no-soap approach, try a salt scrub and your uncertainty will be alleviated.

Stiff Bristle Brush – To help with the salt scrub (as above) a good brush is also a must. We use our Lodge-brand brush so much it rarely even makes it back into the drawer.

Plastic Scraper – For slightly tougher clean-up jobs, I keep a couple of these in my collection. They are also invaluable for scraping out bits of set fat or other pan leftovers that don’t make it onto your plate, either by design or because you’re just too full to eat it.

Chainmail Scrubber – An optional big gun in your arsenal in the war on pan clean up is a heavy-duty scrub pad. I rarely use this personally but for those deeply stubborn bits (or when I’ve let my daughter cook and there are bits of burnt food clinging to the pan) a coarse, seasoning-safe scrubber is worth investing in eventually.

Heavy Duty Oven Mitt – It probably goes without saying, but the best way to use and care for your cast iron is to make it hot. Over a flame, from the oven, or atop a burner, you can neither use it nor care for it if you can’t touch it. Get yourself some serious mitts that will allow you to hold, lift, move, and carry a hot pan without grilling your digits.

Storage Rack – Sure, you could stack your pans one on top of each other — like an animal! Or you could invest in an elegant way to give those pans a way to stack or hang in style. There is probably something to be said about preserving seasoning and preventing damage this way, but the simpler reason is that if you can access them, you can use them.

Self-Cleaning Oven – A dual-purpose tool, a hot oven is vital for seasoning new pans or touching up the ongoing effort to keep your season even and strong. Additionally, a self-cleaning oven can get hot enough on the clean cycle to obliterate all the seasoning layers on a pan that needs a refresh. This is controversial and you shouldn’t do this with antiques or anything you can’t easily replace. Whenever we run the self-clean on our oven, I always toss in a pan or two that are starting to chip or build up seasoning in weird ways. This strips them clean and allows for start a fresh on bare iron.

Fire – Heat is heat, but nothing beats cooking over real fire. Plus, if your pans could talk, they would thank you for the chance to touch some real flames. Not everyone has access to daily fire in the form of a gas stove or barbecue, but taking your pan to a campout or picnic with some burning wood is what your cast iron cookware was made for.