If the coating or seasoning has worn off a cast iron pan, it is still safe to use the pan. In fact, many cast iron enthusiasts prefer to remove the old seasoning and re-season the pan themselves. Seasoning is the layer of polymerized oil that creates a non-stick surface on the cast iron, and it can wear off over time with use and cleaning.
While the seasoning provides a non-stick surface and some protection against rust, it does not affect the safety of the pan for cooking. Even without the seasoning, the cast iron itself is still a safe and effective material for cooking, as long as it is not significantly rusted or damaged.
If your cast iron pan has lost its seasoning, you can easily re-season it by following these steps:
Wash the pan with warm water and mild soap, if needed, to remove any residue.
Dry the pan completely with a towel.
Apply a thin layer of vegetable oil, flaxseed oil, or any other oil suitable for high-temperature cooking to the entire surface of the pan, including the handle.
Wipe off any excess oil with a paper towel.
Place the pan upside down in an oven preheated to around 375°F (190°C) and let it bake for about an hour. Placing aluminum foil on the bottom rack can catch any oil drips during this process.
Turn off the oven and allow the pan to cool down in the oven.
Repeat the oiling and baking process several times if you want to build up a more robust seasoning layer.
Remember that the process of seasoning creates a new layer of seasoning that will be smoother and more effective than the original factory seasoning. With regular maintenance and proper care, your re-seasoned cast iron pan will become more non-stick and enjoyable to cook with over time.