Seasoned cast iron develops a natural nonstick surface through a process called polymerization. When you season a cast iron pan, you apply a layer of oil or fat and heat it. This heating process causes the oil to break down and form a polymerized layer that bonds to the surface of the cast iron. This layer is what provides the nonstick properties.
Unlike nonstick pans with synthetic coatings, the seasoning on cast iron is not prone to peeling or flaking off. The polymerized layer is essentially a durable, solid coating that adheres to the cast iron surface. It forms a protective barrier between the food and the metal, preventing sticking.
When cast iron is heated and cooled repeatedly, the polymerized layer remains stable and retains its nonstick properties. The layer becomes smoother and more resilient with each use and continues to improve over time.
It's important to note that properly maintaining and caring for seasoned cast iron is crucial to preserve its nonstick surface. Avoid using abrasive cleaners or metal utensils that can damage the seasoning. Regularly washing and drying the cast iron after use, and occasionally applying a light coat of oil, helps maintain the nonstick properties and prevent rusting.