First you remove the old seasoning using one of a few methods. That leaves you with bare iron. Then you re-season.
My preferred way to strip a pan of its old seasoning is to heat the pan up to 200F in the oven, then take it outside and spray it with oven cleaner. Then I put it in a trash bag and bring it inside (or leave it outside if it’s summer) and let the oven cleaner do its thing. Rinse and repeat until there is no more seasoning. Wear protective equipment, of course.
Other methods include an electrolysis bath, or using the self-clean cycle on your oven (It’s possible to damage the pan this way, but chances are it’ll be fine).
To re-season, I like to use Crisco.
Warm the pan to 200F in the oven
Remove and apply a coat of Crisco. Be thorough.
Remove excess so you have only a very thin coat of oil
Bring the pan to 300F in the oven for 15 or so minutes
Remove and give the pan an additional wipe down of any excess oil that might have pooled during the 300F cycle
Bake upside down at ~460F (some people do 475F) for 2 hours. The smoking point is above 500F so we leave it just below that to polymerize.
Turn oven off, but leave the pan in while the oven cools down (takes hours).
I do that cycle once a day until the pan looks good. It takes anywhere from 4 to 80 coats. Just kidding about 80, but someone on reddit did that.
The pan will NOT be shiny after seasoning. Seasoning is a permanent layer of polymerized oil. You still need to cook with your favorite cooking oil, which will make the pan shiny.
Washing the pan with soap will leave it looking dull again, because you’ve washed away the cooking oil. The seasoning will still be intact unless you’ve destroyed it some other way (tomatoes are acidic and can wear down the seasoning, putting it in the dishwasher will destroy the seasoning, etc.)
Funny, I actually go over the smoke point to polymerize. I use ghee and cook at 525 for 1 hour, repeating the process for additional layers. It makes beautifully smooth and hard finishes.
Literature on the subject has been highly contradictory in my experience. Some argue that the oil or fat should be below smoke point, and others say it should be over. I personally avoid Crisco, vegetable oil and seed oils in my cooking and I extend that to seasoning as well.
Ghee has worked fantastically for me but it’s another case of he-said-she-said, with half the internet thinking it is the perfect cooking and seasoning fat, and the other half decrying it for a higher rate of spoiled or rancid seasoning — issues I’ve personally yet to come across. Everyone’s mileage varies so much with cast iron, doesn’t it?
A true seasoned surface will only form properly at temperatures well in excess of the 350-375 degree F temperature that some manufacturers recommend for seasoning cast iron. Low temperatures do not completely polymerize and break down oil and will leave a brown, somewhat sticky pan instead of a black, non-stick one. 400-500 degrees F is the effective range for seasoning.
From Dave Arnold’s excellent blog ‘Cooking Issues’
I always thought you were supposed to go over the smoke point, but I did a bit of reading recently and found one source that sounded confident that staying below the smoke point still results in polymerization. There was also conflicting information on the actual smoke point of shortening, anywhere from 490-525F. So far 470 is working well, but whether the seasoning is durable long term is yet to be seen.
There’s still a “smoking oil” smell in the kitchen so I leave the fan running, but there’s no visible smoke. I think with the oven set to 470F, there’s probably enough radiant heat from the oven coils to bring the iron up to 490+, at least for a little bit. That’s just an unscientific guess, though.
First you remove the old seasoning using one of a few methods. That leaves you with bare iron. Then you re-season.
My preferred way to strip a pan of its old seasoning is to heat the pan up to 200F in the oven, then take it outside and spray it with oven cleaner. Then I put it in a trash bag and bring it inside (or leave it outside if it’s summer) and let the oven cleaner do its thing. Rinse and repeat until there is no more seasoning. Wear protective equipment, of course.
Other methods include an electrolysis bath, or using the self-clean cycle on your oven (It’s possible to damage the pan this way, but chances are it’ll be fine).
To re-season, I like to use Crisco.
I do that cycle once a day until the pan looks good. It takes anywhere from 4 to 80 coats. Just kidding about 80, but someone on reddit did that.
The pan will NOT be shiny after seasoning. Seasoning is a permanent layer of polymerized oil. You still need to cook with your favorite cooking oil, which will make the pan shiny.
Washing the pan with soap will leave it looking dull again, because you’ve washed away the cooking oil. The seasoning will still be intact unless you’ve destroyed it some other way (tomatoes are acidic and can wear down the seasoning, putting it in the dishwasher will destroy the seasoning, etc.)
Funny, I actually go over the smoke point to polymerize. I use ghee and cook at 525 for 1 hour, repeating the process for additional layers. It makes beautifully smooth and hard finishes.
Literature on the subject has been highly contradictory in my experience. Some argue that the oil or fat should be below smoke point, and others say it should be over. I personally avoid Crisco, vegetable oil and seed oils in my cooking and I extend that to seasoning as well.
Ghee has worked fantastically for me but it’s another case of he-said-she-said, with half the internet thinking it is the perfect cooking and seasoning fat, and the other half decrying it for a higher rate of spoiled or rancid seasoning — issues I’ve personally yet to come across. Everyone’s mileage varies so much with cast iron, doesn’t it?
From Dave Arnold’s excellent blog ‘Cooking Issues’
https://cookingissues.com/2010/02/16/heavy-metal-the-science-of-cast-iron-cooking/
I always thought you were supposed to go over the smoke point, but I did a bit of reading recently and found one source that sounded confident that staying below the smoke point still results in polymerization. There was also conflicting information on the actual smoke point of shortening, anywhere from 490-525F. So far 470 is working well, but whether the seasoning is durable long term is yet to be seen.
There’s still a “smoking oil” smell in the kitchen so I leave the fan running, but there’s no visible smoke. I think with the oven set to 470F, there’s probably enough radiant heat from the oven coils to bring the iron up to 490+, at least for a little bit. That’s just an unscientific guess, though.