Flat grills, just like any other cast iron pan, need to be seasoned before using. Seasoning your flat grill should also be done after long periods of storage, or if the grill was allowed to rust. Cast iron grills can last decades, when properly cared for.
Seasoning Your New Flat Grill
Preheat your oven to 275 degrees.
Coat the top of the flat grill with lard or bacon fat. If you use vegetable oil, it will leave the grill sticky when cooled.
Place the coated flat grill in the preheated oven for 15 minutes.
Remove the flat grill from the oven and pour off any excess grease.
Return the flat grill to the oven and leave it for two hours.
Repeat steps 1 through 5 several times. This will create a non-stick surface and protect the flat grill from rust.
Clean the grill with a scouring pad and hot water, to remove food and rust. Heating the grill slightly will help remove stuck on food.
Dry the flat grill immediately with a cloth or paper towel. Don't let water stand in your cast iron: It will rust.