Things You'll Need
Fine sandpaper or steel wool
Cast iron pipes are very durable and designed to last for many years. However, while cast iron is tough and heavy, it does corrode over time. Oxidation occurs when water and oxygen interact with the iron to form a coating of rust over the pipe. The rust will eventually spread through the iron if it is not removed and will cause holes and a general weakening of the pipe. Cleaning corroded cast iron pipes requires a lot of effort but the process helps the pipes look better while it also keeps them in better condition for a longer period of time.
Rub fine sandpaper or steel wool against the iron pipe to grind away smaller rust spots.
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Pour white vinegar in a spray bottle. Spray the corroded areas of the pipe with the vinegar, sprinkle salt on top and then scrub the areas with a scouring pad. The acidity of the vinegar helps break down rust while the salt both degrades the rust and increases the friction of the scouring pad.
Use a rust remover on the cast iron pipe if the previous milder methods are not effective. Rust removers are highly corrosive so wear protective gloves to prevent skin exposure. Follow all instructions on the chemical's packaging for best results and to maintain safety. Allow the rust remover to soak into the corrosion and then scrub at it with either a cloth or a scouring pad. Reapply sandpaper or steel wool afterward and rinse the pipe off once the corrosion has been removed.
Repeat the steps until all the corrosion is gone. It typically requires a lot of physical effort to scrub all the rust or corrosion off a cast iron pipe.