A properly seasoned cast iron pan should not rust or tarnish, even if you don't use soap on it. In fact, using soap on a seasoned cast iron pan is generally not recommended because it can strip away the seasoning, which is a natural layer of polymerized oil that forms on the surface of the pan through repeated use and heat.
The seasoning on a cast iron pan creates a non-stick surface and helps protect the iron from moisture and rust. When you cook with oils and fats, they bond with the iron and create this protective layer. However, soap is designed to break down oils and remove them, which is why using it on cast iron can be problematic.
To clean a seasoned cast iron pan, you should follow these steps:
- Let the pan cool down slightly after cooking.
- Use a soft sponge or brush and hot water to scrub away any food residue. You can also use a small amount of kosher salt as an abrasive if needed.
- Rinse the pan thoroughly with hot water.
- Dry the pan completely with a towel or by placing it on a stovetop over low heat to evaporate any remaining moisture.
- Optional: Apply a thin layer of oil to the pan while it's still warm to help maintain its seasoning.
By avoiding soap and properly maintaining the seasoning, your cast iron pan should remain rust-free and in excellent condition for many years. If you notice any rust spots developing due to improper care or accidentally leaving the pan wet, you can remove the rust with a gentle scrubbing using steel wool or a non-metallic scrubbing pad and then re-season the pan to restore its protective coating.