I have read all of these comments and feel compelled to offer my two cents into the mix. I know there are all kinds of “best” ways to restore cast iron but there are a few things to stay away from if you want to keep your iron useable for years to come.
First of all, do you use your iron on a daily basis or more than twice a week? Or do you bring it out whenever the urge strikes, cook something in it, and store it for another 4 to 6 months before pulling it out again? The difference will make a difference in what kind of oil you use to season your pan. I have used bacon fat [my favorite choice] or good ol’ Crisco [my 2nd favorite choice]before putting the pan away. if you use your iron on a regularl basis, there should be no problem with either of these or with lard or any other animal based fats if you are heating the pan more than once every few weeks or months. The problem comes from using the pan to cook a meal on January 1st and then not dragging out the iron again until the 4th of July! Leaving a cast iron pan or Dutch oven or any other cast iron kitchen utensil, for that matter, in the closet for that long with most any animal based fat for seasoning will probably encourage the coating to turn rancid the same way that a jelly jar of bacon fat sitting on the counter for months will probably get pretty ripe from not using it or storing it improperly for that long of a time.
Reading: How to clean rust off cast iron
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Regarding removing rust by putting the cast iron in the oven on a “cleaning” cycle, keep in mind that should that iron warp from the extended length of time at up to 550 F. during the cleaning cycle, you will not be able to “unwarp” it once the bottom is round. That was one of the reasons why many old cast iron manufacturers would put a raised “ring” around the bottom of their iron to minimize the amount of direct contact with certain types of heat sources. Lodge, I noticed, still has a raised ring on most of their cast iron made today. Remember that the cleaning cycle’s purpose is to incinerate to ash everything of an organic origin that has dripped, flaked off, or otherwise arrived in the bottom of the oven or hanging from the racks.
I am sure that there will be those who will argue my tactics so I will close by saying that my family, going back to my grandparents [to my knowledge], have passed down these tips to keep cast iron serviceable. I am 77 as I type this so that spans a couple of long generations to use what worked for them and for me also.
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