How to season cast iron
Cast iron pans can be the most versatile and hard-wearing pans you’ll buy, but they require a bit of easy maintenance. Learn to do this properly and you’ll have pans that will last beyond a lifetime.
The terms ‘seasoned’ or ‘seasoning’ when you’re talking about cast iron has nothing to do with salt and pepper. It refers to a thin, fat-based layer on the surface of the pan that, when heated to a high temperature, forms a coating on the iron (a process called polymerisation) and stops food from sticking and the pan from rusting.
Seasoning is not about adding flavour to the pan or not washing the pan to allow the layer of cooking oil to build up. It’s about maintaining that coating so you get the most out of your pan and it lasts for as long as possible. Most new cast iron pans now come pre-seasoned, but the more you lightly season your pan after using it, the more ‘non-stick’ it will become. As cast iron is such a sturdy piece of kitchen kit, buying pans second hand is a great option and – unless they are cracked – learning to season cast iron can bring even the most neglected pans back to life.
Once it has a well-seasoned patina, a cast iron pan can work as a frying pan, a wok, a stove-to-oven roasting pan, a pie or tarte tatin dish. It can be used for open fire cooking or in pizza ovens and for dishes such as omelettes, frittatas, and pancakes. When you need to guarantee the food you’re cooking won’t stick then a well-seasoned cast iron pan is the item to reach for. These satisfyingly heavy, heat-retaining pans – when looked after – should outlast you, which makes them a great choice when it comes to sustainability in the kitchen, but you’ll need to show them a bit of care and attention to keep them happy and get the best out of them.
How to season cast iron
Whichever method you chose, seasoning cast iron will create a bit of smoke so turn on your extraction and get as much ventilation going through the kitchen as possible.
- Wash and dry the pan well – If the pan is new or just new to you give it a good wash in hot soapy water. You can use a sponge and gentle scourer or brush but avoid anything metallic or too abrasive. Give the pan a thorough dry with a towel, if there looks like there is still some damp patches on the pan, heat it over a medium flame until completely dry.
- Oil the pan – Use a piece of folded kitchen paper to rub a small amount of sunflower or vegetable oil (see tip below) all over the pan including the handle (if it’s cast iron) and the outside. A very thin coating is desirable, there shouldn’t be any excess drips of oil anywhere. Your aim is to buff the pan with oil, leaving the thinnest coating possible.
- Heat the pan – Put the pan over a medium-high flame, if you an induction hob, see the oven tip below. Leave the pan to heat up and smoke a little, when the smoke has died down, the pan is seasoned. To add another layer, apply some more oil (using tongs and the kitchen paper this time as the pan will be very hot) and put over a medium heat again. You’re after a shiny layer that’s coated to the pan. Do this to pans regularly and your grandchildren will be passing the pans onto their grandchildren.
The oven method
If you don’t have a flame to season your pan over then another way to do it is in the oven. This is an easier and more even way of seasoning cast iron, but it will mean using a lot of excess energy to do it.
To season in the oven, heat the oven to 240C/220C fan/gas 9. Buff the pan with oil as stated above then put the pan, upside down, on the oven rack with a tray on the rack below to catch any potential drips of excess oil (but if you’ve buffed it properly there shouldn’t be any drips). Leave the pan for 40 mins until the oil has coated the pan then reapply if needed.
What oil should I use to season cast iron?
Cast iron pan companies recommend cold-pressed flax or flaxseed oil and there’s science that says this is the most efficient oil for polymerisation as it sets hardest but it’s expensive and certainly not essential. Of the oils you already have in the kitchen, the best ones to use are a neutral frying oil like sunflower, vegetable, peanut or non-virgin/light olive oil. Extra-virgin olive oil is a waste of money and won’t work as well. Similarly, flavoured oils like sesame, hazelnut or walnut will leave an acrid flavour and not coat the pan as well. We must state that whatever oil you use it needs to be an edible cooking oil.
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What temperature should I use when seasoning cast iron?
For the oil to form a shiny non-stick coating (polymerisation) it needs to go past its smoking point. If you’re seasoning the pan over a flame then you want the pan on a medium-high heat.
If using the oven method, set the oven to very high or 240C/220C fan/gas 9 – which is about as high as most ovens go. The process will take a lot longer in the oven and if the pan feels sticky rather than smooth then the process isn’t complete, and you’ll need to pop it back in the oven for longer.
How often should I season cast iron?
The amount of oil layers or seasonings you give a pan depends on the state of the pan. For general upkeep, one to two seasonings will keep the pan happy. But if you’re bringing the pan back to life, and it’s rusty or has food crusted to it, then the more you season it the better it will become so six to eight times would revive it, but remember the kitchen is likely to get smokey.
How to remove rust from cast iron
If a cast iron pan isn’t dried properly or exposed to moisture for too long, it can rust. But with a bit of elbow grease it can be brought back to life (great to know if you find a cheap neglected second-hand pan). To get rid of the rust you’ll need to be a bit more heavy-handed with the pan. Scrub the pan thoroughly with an abrasive scourer then dry fully, doing this over a low flame is best. Now, there’s lots of different advice online, some people say to soak the pan in a white vinegar and water solution, other make a paste with baking powder but we found that just using dry table salt works well.
- Sprinkle the pan very liberally with the salt and use a dry piece of folded kitchen paper to scrub the salt into the pan and soon the salt will change from white to a rusty grey – that means it's working and removing the rust
- Throw the salt away and add more salt and keep on doing this until there is no more rust, then it’s a matter of washing the pan again and seasoning it well
How to deep clean cast iron
If something you’ve cooked has crusted itself to the pan the easiest time to get it off is when the pan is warm. If something has welded itself to the pan then getting the pan back to it’s original sheen is the same process as removing rust.
How to clean enamelled cast iron
All the instructions we give in this article are for black cast iron pans which are sometimes referred to as skillets for shallow pans and Dutch ovens for the deeper lidded pans. Enamel lined cast iron pans can just be treated like any other saucepan – washed in the dishwasher – but shouldn’t be used over open fire.