Dip in Vinegar
Dip your cast iron is 1 part vinegar and 1 part water. The vinegar is corrosive to metals and this is why it will peel away the layers of rust. After 20 minutes, remove the item from vinegar and start scrubbing with steel wool. Use a string dish soap to get rid of rust. Wash and coat with oil to avoid rust.
Electrolysis
The cast iron can be cleaned effectively with electrolysis. You’ll have to head to a hardware store to get the tools you need or you’ll have to get it done by a professional. Look for a local repair shop that offers such services. Getting an old cast iron pan cleaned properly will make the pan as good as new.
Naval Jelly
Things like vinegar work really well with small, compact products. But, if you're dealing with rust on a BBQ grill, mailboxes, fences, etc., you could use naval jelly. However, it's important to note that this solution is really harsh on thin metal. It should only be used on objects with thick coats of metal. Spray or paint the jelly on the rusted parts. They'll start clearing up in 5-10 minutes of application.
Warm Water
Dip the cast iron utensils in a bucket of warm water. You can also add some mild dishwashing soap to create lather and breakdown the rust layers. Wait for 10 minutes and then use a scrubber or a brush to scrape off all the rust.
Baking Soda
To remove a tough layer of rust from your cast iron pan, wet the surface with water and place it in the sink. You just need to pour enough water that adds a thin layer of water to the surface. Sprinkle baking soda on it and spread it onto the entire surface. Take a brush or steel wool and start scrubbing. Gradually add some dishwashing soap and go on scrubbing until your start to notice the surface of cast iron losing the rust. Wash the pan and check if the rust has come off. If there are any stubborn rusty spots left, repeat the process. Pour some oil and rub it on the pan to make it rust-proof.
Ideally, you should wear gloves before scrubbing before you’ll have to scrub it for long enough until the rust comes off and the process can damage your nails. Always wear rubber gloves when removing rust from cast iron.
