Don't so these things, take care of your equipment.
Never put cast iron cookware in a dishwasher! The high heat, moisture, and detergent will remove the seasoning and cause rust.
• Do not expose cast iron cookware to excessive heat above cooking and seasoning
temperatures! Refrain from placing cast iron cookware in a self-cleaning oven cycle, a gas grill turned on HIGH, buried in the hottest coals of a campfire, or other high heat sources for an extended period of time. This can cause the unit to turn a reddish color (not rust) and will most certainly warp.
• Never place cast iron on a cooktop element that is already hot! This can cause the unit to crack or warp.
• Failure to pre-heat cast iron gradually can cause cracks to form in the cookware.
• Cast iron will be hot during and after use; always use insulated mitts or gloves for
protection from hot surfaces or splatter from cooking liquids.
• If cast iron cookware or cooking oil ever begins to smoke, immediately remove it from the heat source. Overheating like this can burn off seasoning, cause smoke or fire damage.