Baking pans are composed of a variety of different metals and coatings that are designed to aid in the baking of the specific baked good of your choice. While rust can potentially harbor bacteria, which leads to ailments such as tetanus, a small amount of rust or discoloration on your pan may not be harmful if you have thoroughly scrubbed and cleaned the pan, removing the majority of rust and discoloration on the interior of the pan. As iron oxidizes, rust forms on the exterior of the metal. Rust can also form on iron's other alloy metals, such as steel.
Health Concerns and Coating
While rusty iron is not an ideal baking surface, your major concern if you notice rust forming on the inside of your pan should be with regards to the coating on your pan. While many iron and cast iron pans don't have a coating, other, more cheaply made pans and pans with nonstick surfaces contain harmful chemicals that can flake off into your food when rust forms on the inside of your pan. As a result, if any of your pans have a prior coating and rust forming, throw them out immediately. If not, then the rust that you're dealing with is simple iron rust and can be properly cleaned.
Scrub and Sand
If you have noticed rust on your iron or steel baking pan, it is possible for you to remove the majority of the external rust using abrasive pads and pumice cleaner. To start, apply cleaner to the part of the pan that you want to clean. Rub the spot firmly and thoroughly with an abrasive pad until the rust begins to flake off. Rinse the pan out to see if there's any rust left. If there's rust left, you will have to sand the pan using wet/dry sandpaper. Wet the pan before using the sandpaper, applying it firmly and using multiple pieces of sandpaper until you've removed the rust.
Once you've successfully removed rust from your baking pans, it's essential that you season the pan to ensure that rust won't return. Seasoning prevents metals from oxidizing by preventing moisture and oxygen from getting on the exposed metal. To season your pan, cover it with fat, grease or oil prior to baking to help prevent it from oxidizing. Once you've cleaned your pan after baking it, reapply a small amount of oil or fat before covering your pan and putting it away.
While rusty baking pans can be cleaned and reused, use caution when cooking with a rusty baking pan. If you notice rust that is flaking off on the inside of the pan, don't use it. While rust is a concern for some bakers, another more pressing concern is the type of metal that you use to cook with and if it's leaching into the food while heated. Certain low priced cookware are composed with enamel coatings that chip and wear out, seeping into your food and causing potential health risks. As a result, buying higher quality products will help insure that the coating won't chip off into your food.