Putting a cast-iron pan directly in water can lead to rusting, but it won't necessarily ruin the pan forever. Cast iron is susceptible to rust because it contains iron and carbon, and when exposed to moisture, it undergoes a chemical reaction that results in iron oxide, commonly known as rust.
When the pan is exposed to water or moisture, the iron reacts with oxygen in the air to form rust. Rusting can degrade the seasoning (the polymerized oil layer that provides a natural non-stick surface) on the pan and lead to surface imperfections, making it less smooth.
To prevent rusting and properly care for your cast-iron pan, follow these steps:
Avoid soaking: Never leave your cast-iron pan in water for an extended period. Avoid soaking it or leaving it to air dry after washing.
Hand wash promptly: After cooking, hand wash the pan with hot water and a soft brush or sponge. Avoid using harsh detergents that can strip away the seasoning.
Dry thoroughly: After washing, dry the pan thoroughly with a clean towel. To ensure all moisture is removed, you can place it on the stovetop over low heat for a few minutes.
Re-season when needed: If you notice rust or the seasoning wearing off, it's time to re-season your cast-iron pan. To do this, apply a thin layer of vegetable oil or flaxseed oil all over the pan's surface, including the handle, and bake it upside down in an oven at a specific temperature for a specific time (follow the manufacturer's instructions or look up a reliable source for the proper re-seasoning process).
Store properly: Store your cast-iron pan in a dry place. If you need to stack them, place a paper towel or cloth between pans to prevent moisture buildup.
Use regularly: Regular use of your cast-iron pan can help maintain its seasoning and prevent rust. The natural oils from cooking will contribute to the seasoning process.
By following these care tips, you can prevent rusting and keep your cast-iron pan in excellent condition for many years of use. If rust does occur, it's usually fixable with proper re-seasoning and care, so there's no need to worry about ruining the pan permanently.