Firstly, can cast iron rust?
Good question. The answer is yes, cast iron rusts when it is oxidised and exposed to water. It’s just like any other iron. so, if you leave liquid in the cast iron, it will rust. But if you clean and season it properly, you’ll be fine.
Cast iron is known for its durability, long-lasting functionality, and beautiful design. But it’s not always made to last. Sometimes small levels of surface rusting is a sign of good care, such as in the case of cast iron pots and pans. But rusting can also indicate that maintenance is needed. If you’ve been noticing rusting, it might be time to perform the necessary maintenance.
The treatment of a cast iron pan (seasoning) makes it resistant to rust.
When you season a cast iron skillet, you heat oil on the surface of the pan, which polymerizes the oil so that the resulting molecules can cross link and mechanically bond to the griddle and seal the surface.
Most people are afraid to use soap because they are afraid to dissolve the spice, but since the oil polymerizes, it will not happen.
What can happen is that excessive use of tools or cleaning agents can scrape when seasoning. That’s why it’s good to season again from time to time.
When cast iron rusts?
It rusts because the rate at which it oxidizes is relative to the environment and humidity. Good quality thick cast iron does not rust quickly, although rust is permeable because the rust itself protects the underlying surface.
Oxygen has to reach the tasty iron atoms to produce iron oxide, and for that it needs a surface area.
Cast iron brake discs can develop a thin layer of rust in a few minutes in very humid situations.
Is it safe to use a rusty cast iron skillet?
Using a minimally rusty cast iron skillet might be safe if you remove the rust, re-season the skillet, and monitor it for further rusting. However, if the rust is extensive or the skillet is heavily pitted, it’s best to avoid using it for cooking. Be cautious with acidic foods. If unsure, seek a professional’s opinion.
If it has too much rust and has leaked into deeper layers of your cast iron cookware, you should throw it away. Sometimes there is too much rust for recovery. However, if you have thin layers of rust, you should be able to restore your cast iron skillet.
Basically, that means brush it with a wire to remove loose rust and then clean it well with an old-style carbon steel fiber sponge. When you’re done, dry it well and then clean it with cooking oil and heat it to bake the oil (it will “dry” like paint). Repeat the process several times to prevent the pan from rusting again.
