You can’t burn rust off cast iron, because rust is a metal that’s already been oxidised, ever seen a fire pit? Yes they can be rusty even with the extreme temperatures they undergo, this is proof that you can’t burn rust, that means, regardless of which cast iron equipment you have, whether it’s a cast iron pan or a grill, you can’t use heat to clean the rust.
The exception to this is thermite, but this is a story for another time, as it won’t help you today.
Preventing rust on cast iron is a great guide that we have. Alternatively seasoning your cast iron skillet should help a lot in preventing rust.
Remove rust from cast iron with salt
Removing rust from cast iron with salt is simple, there is no chemistry involved with this, you are simply using the salt as an abrasive.
Pour some salt onto your cast iron, and use something to wipe it around with such as a dry cloth. The salt will act as an abrasive and clean off any surface rust.
If you have anything more severe than surface rust, you’ll need to look at restoring your cast iron.
Remove rust from cast iron with vinegar
Using vinegar to remove rust from cast iron is a good technique, as long as it’s surface rust. The vinegar will dissolve the rust and turn it into a paste.
Simple wrap your cast iron in a plastic bag that’s preferably waterproof. Add some vinegar, and let it soak for around an hour.
After an hour, the rust should be in a form of paste, and you can wipe it away.
How fast does cast iron rust?
In general, rusting is an oxidation process. Rust will form when iron reacts with oxygen or moisture in the air. It usually begins in a few layers of metal, but can progress deeper into the material as time and temperature increase. Between these two extremes, there are factors that affect the rate of rusting.
The environmental conditions in which the iron is stored, for example air humidity and temperature (especially whilst storing), play an important role.
The temperature at which the iron has been stored is also important but not essential. In general, rust will form more rapidly at a higher temperature without protection from air condensation, such as with a cast iron skillet that has been left outdoors in warm weather.
Preventing rust on cast iron
The best way to prevent your cast iron from rusting is to avoid storing it in damp conditions, keeping it coated with oil and to store it somewhere warm.
If you’re storing your cast iron for long periods of time, say a few months or more, then you may want to re-coat it after you’ve used it. This will help maintain the seasoning and prevent rust from forming. If the rust is too bad, then it may be time to throw away your cast iron skillet.
You can read more about preventing rust here.