The oily film or residue found on the bottom of a new cast-iron pan is often a result of the manufacturing and packaging process. It serves as a protective coating to prevent the pan from rusting while in storage or during transportation. This coating is typically a thin layer of oil or grease applied to the pan's surface.
The purpose of this oily film is to provide temporary corrosion protection until the pan is purchased and ready for use. However, it can make the pan slippery and challenging to clean off. Here are some steps you can take to remove the oily film and prepare the pan for seasoning:
Wash the pan: Start by washing the pan with hot water and a mild dish soap. Use a non-abrasive sponge or brush to gently scrub the surface and remove any visible residue. Avoid using harsh cleaning agents or scouring pads that can damage the pan.
Rinse and dry thoroughly: After washing, rinse the pan thoroughly to remove any soap residue. Pat it dry using a clean towel or paper towels.
Remove remaining oil: If the oily film persists, you can use a small amount of mild detergent or a kitchen degreaser specifically formulated for removing oil. Apply it to the pan's surface, scrub gently, and rinse well. Ensure that you remove all traces of the cleaning agent before proceeding.
Season the pan: Once the pan is clean and dry, it's essential to season it before use. Seasoning creates a natural nonstick surface and helps protect the cast iron from rusting. To season, apply a thin layer of cooking oil (such as vegetable oil or flaxseed oil) to the entire surface of the pan, inside and out. Wipe away any excess oil, place the pan in an oven preheated to a specific temperature (follow the seasoning instructions provided by the manufacturer), and bake it for a designated duration. This process polymerizes the oil and forms a protective layer.
By following these steps, you should be able to remove the initial oily film from the bottom of the cast-iron pan and prepare it for seasoning and future use.