We do not recommend using Calcium, Lime and Rust Remover on cast iron. The acids in Calcium, Lime and Rust Remover can compromise the metal.
The manufacturer doesn't recommend it for cast iron as it can apparently compromise the metal. So I wouldn't do it.
All you need is hot water and a scrubbing brush, steel wool or a copper cleaning cloth to do this. You can use kosher salt, a scrubber and neutral oil to scrub it. Important- do NOT use any soap. If you find it difficult to remove, you can leave water in the pan overnight to soften the debris.
The vinegar solution will dissolve the rust, but once that's gone, it can penetrate further and start eating away at the original cast surface of the pan, the ultimate death sentence for your skillet.
Cast iron needs to be cherished, and rust is the enemy. The easiest and fastest way to remove rust from cast iron is Evapo-Rust®. It will spare your knuckles, as there is no scrubbing with brushes or steel wool involved. It is also safe to use on your cooking supplies.
Gently scrub the pan using mild dish soap, hot water, and a non-abrasive sponge (such as a Dobie sponge or the soft side of a Scotch-Brite sponge) or a scrub brush. Rinse it clean and then dry it completely with a dish towel.
WD-40 can be used to remove rust from your cast-iron stovetop depending on how much you use and how long you leave it there. If you want to get rid of it quickly, you can try adding more WD-40 or applying the same layer over again.
It's important to not use anything too aggressive such as steel wool, sponges or other abrasive cleaning methods as these will strip your seasoning. For particularly difficult to clean messes, fill your pan halfway full with water and heat over the stove.
Fill your dutch oven with water and bring it to a boil. Then add a few big spoonfuls of baking soda (add them slowly as the baking soda will bubble up and foam). Let the mixture simmer on the stove as you use a wooden spoon to scrape up the blackened, burnt-on stains.
CLR is corrosive. Avoid contact with wood, clothing, wallpaper and carpeting. Some laminated surfaces (counter tops) are coated with a synthetic surface which may be affected by rust removers; clean spills immediately.
Caron Doucet Cast Iron Soap
The oil that you use to season a skillet is so well-bonded to the pan that detergent won't hurt it. Bonus: The Caron Doucet soap, specially formulated to clean cast iron, is also 100% natural and free of parabens and synthetic foaming agents.
It really depends on what kind of cleaning you need to do. If you're dealing with really tough, built-up mineral deposits, especially in your bathroom or kitchen, CLR might be the way to go. It's strong enough to handle stains that vinegar might struggle with.
Bar Keeper's Friend or baking soda will take care of any stubborn spots, and when you're done cleaning: just dry off and put it away. No seasoning required.
Add hot water: Wash the skillet by hand using hot water and a sponge or stiff brush (here's our favorite brush, which is designed specifically for cast-iron). Avoid using the dishwasher, soap, or steel wool, as these may strip the pan's seasoning. Make sure to use tongs or wear gloves if the water is extra hot!
White vinegar
The mild acid can dissolve limescale and disinfect. All you need to do is pour a generous amount of white vinegar down your toilet bowl, let it soak in overnight, then scrub with a brush. Then flush to rinse, and voilà, your toilet is back to its former whiteness!
Empty any water from the reservoir and add distilled water or a mixture of 1/4 cup white vinegar and 3/4 cup distilled water. Run the iron on full steam. Gently move the iron to and fro over a bowl. Water and steam will wash any scale and dust through the soleplate.
White vinegar – white vinegar can help you here, but check the manufacturer's instructions first as putting vinegar in the reservoir may not be recommended for your model. Mix equal amounts of vinegar and water, put the mixture in the reservoir, turn the iron to medium heat and give it about ten minutes to steam.