Remove Rust with a Potato! Cut the raw potato, dip cut end in baking soda or dish soap and rub over rusted area. If potato gets slick, cut again and repeat. Then rinse and dry well. The oxalic acid in the potato helps to dissolve the rust.
How To Clean and Season an Old, Rusty Cast Iron Skillet
How To: Restoring & Seasoning Cast Iron Pans. Found about 10 cast iron pots/pans in the France house and all need restoring but my old wood-fired cuisiniere doesn't have a self-cleaning function so will have to adapt the method!
17 Genius Tips & Tricks For If You Own A Slow Cooker