It's a fact of life that oxygen and iron combine to produce rust, and if you find yourself bothered by the corrosion disfiguring your gutters or fouling your skillet bother, be grateful you don't live on Mars; the entire Red Planet is covered with iron oxide dust. Rust is difficult to control, but control it you must if you plan to keep the metal in your life serviceable and in one piece. You can get rid of it by mechanical means, by dissolving it with chemicals or by converting it to a harmless powder with different chemicals.
Scrape, Sand or Grind It
The non-chemical approach to removing rust is to simply roll up your sleeves and physically remove it. Because you don't have to wait for a chemical reaction to occur, this is often the fastest approach. Useful tools include:
- A wire brush. These come in various sizes and are best for rigid metal surfaces. If you need delicate scrubbing action on a smaller surface, use a hard-bristle toothbrush.
- Sandpaper. With or without a machine, sanding removes rust from most surfaces, and it's the best option if it's important to leave delicate surfaces smooth. Steel wool and crumpled-up tin foil also remove rust in a gentle way.
- A grinder. Use a 4-inch angle grinder for large jobs and a rotary tool with a grinding accessory for small ones. Whichever tool you use, grinding is the most aggressive rust-removal technique you can choose.
You can dissolve iron oxide with an acid, and the stronger the acid, the better it works. Commercial rust dissolvers usually contain hydrochloric or phosphoric acid, and they can be dangerous and unpleasant to use. Always follow the instructions on the container of whatever product you're using. Some household chemicals are alternatives that require prolonged contact -- often by soaking -- but are safer to use. They include:
- white vinegar, which dissolves rust by virtue of the acetic acid it contains.
- lemon or lime juice, which both contain citric acid.
- your favorite cola, which gets its tartness from phosphoric acid.
- a potato, which contains oxalic acid, makes a great cleaning implement for rusty knives. Just add salt ... to enhance the chemical reaction.
In addition, although it's alkaline, baking soda can also dissolve rust safely from kitchen and bathroom implements. Just make a paste with water, spread it on the rust, let it work for an hour or two, and brush it off with steel wool or a toothbrush.
Another way to deal with rust is to turn it into something useful, and that's how a rust converter works. The tannic acid in a rust converter turns iron oxide into iron tannate, which is a stable chemical that won't react with oxygen. Rust converters often contain a polymer coating, which covers the rust and protects it from further deterioration -- essentially acting as a primer. Use a converter by brushing it on the rust according to the directions on the container and giving it the recommended time to do its work. The surface must be clean and free of oils and grease, so some surface preparation is required.