Rust 101: Give New Life to Ugly Metal

Rust 101: Give New Life to Ugly Metal
(Yuriy Golub/Shutterstock)
12/1/2022
Updated:
12/1/2022

Rust is like a cancer in that it keeps growing, looks unsightly, and eats away at its host—in this case, metal—weakening and destroying it. You need to stop it ASAP.

From outdoor furniture, mailboxes, and the tools you left out in the rain to jewelry, cast iron pots and pans, and parts of your car, rust occurs just about everywhere that metal containing iron (including many kinds of steel) comes into prolonged contact with water and oxygen. This combination results in oxidation, better known as rust.

Keeping metal surfaces dry goes a long way toward preventing rust, but of course, this isn’t realistic in most cases, and most of us don’t even discover the problem until rust is already present. If the rust isn’t bad, a light rubbing with sandpaper, steel wool, or a wire brush might be all that’s needed to remove it, revealing good metal underneath. But even if you’re working with a seriously deteriorated metal, you want to start by removing any loose pieces of rust first before moving on to more brawny treatments.

Acetic Answer

Commercial rust reformers (also called rust neutralizers and rust converters) do a great job in extreme situations, but they normally use harsh chemicals to do so. Before you head to the store, look around the kitchen. If you have a bottle of white vinegar, its acetic acid (a result of its fermentation process) might be all that you need. White vinegar is perfect for soaking small tools, parts, or jewelry.
But before you take your glitters for a dip, pause to make sure we’re dealing with rust, not tarnish. Rust is an orange/brown color, while tarnish creates a gray or black coating on silver, copper, and brass, which normally don’t rust. (If you’re dealing with tarnish, you can reference my metal cleaning tips here.)

White vinegar can also be wiped over a surface with a damp cloth, or poured over items such as stuck bolts to help loosen them. Let it sit for at least 30 minutes. To bump up the power, add salt at a rate of 1/4 cup of salt to a quart of vinegar to increase the acidity, allowing it to work faster. Some very rusty items may need to be soaked overnight.

Afterward, use an abrasive pad or brass bristle brush to remove any remaining rust. Rinse the item down thoroughly, then soak it in a 50/50 mixture of water and baking soda to neutralize the vinegar. Restore the shine with a brisk buffing, using very fine 0000 steel wool. Dry the piece thoroughly with a cloth soaked in denatured alcohol, then protect it with a coating of camellia oil (used to keep tools rust-free for generations), a clear coat designed for metal, or prime and paint it.

Chemical Solution

Commercial rust reformers, comprised of tannic or phosphoric acid, convert the existing iron oxide (rust) into a protective chemical barrier that protects the surface from further damage. Tannic acid is a top choice for outdoor applications as it results in a protective bluish-black inert ferric tannate layer that can be left alone; although, you can paint it with an oil or epoxy-based paint for aesthetic reasons.

Phosphoric acid, on the other hand, turns the rust into an inert layer of ferric phosphate that can be left alone for indoor use, but must be painted if the item will be used outdoors and exposed to weather. It should also be noted that while both are designed to work on iron and steel, they will not work on aluminum, copper, stainless steel, or galvanized metal. They also require some preparation.

Knock off loose or flaky rust with a wire brush or sandpaper before applying the converter. DO NOT remove all of the rust, just the loose stuff. You need some rust for the converter to work with. Then, apply as directed in a well-ventilated area, wearing proper safety gear including gloves and eye protection. Rust reformers are the best choice when you need fast results or you’ve got a large area of rust to treat.

Rust Encapsulators

If you’re going to be painting the metal anyway, and you’re dealing with light surface rust, you may want to consider a “paint over the rust” encapsulator. The entire area doesn’t even have to be rusty; encapsulators work on rusty and good metal alike. They are available as brush-on and spray-on coatings that bond with rusty metal to instantly transform it into a non-rusting surface. Just clean the surface—no sanding or scraping is required—and apply. The coating acts as a primer for your paint of choice.

Homespun Helpers

Coke and other soft drinks with phosphoric acid in them make great rust removers; read on for more kitchen wisdom.

When Life Gives You Lemons

Mix borax and lemon juice to form a paste. Apply to the rusted spot, and let sit for at least 30 minutes. If the paste dries out, spray it with water to rewet it. Scrub with a toothbrush. Repeat if needed. When done, rinse thoroughly to make sure there’s no citric acid remaining.

More than Cakes

Sprinkle baking soda on the rust, making sure it is completely covered. Wet a scrubbing pad (it needs to be wet to prevent it from scratching the surface) and begin to scrub, adding baking soda when it begins to dissolve. Continue until all the rust is gone.

Cast Iron Secret

Rusty cast iron pans are a dilemma; you don’t want to use any harsh or toxic cleaners on them—but you don’t need to. Cut a potato in half, dip it in dish soap or baking soda, and give the rust a firm rub down. The oxalic acid in the potato will do the rest.
Sandy Lindsey is an award-winning writer who covers home, gardening, DIY projects, pets, and boating. She has two books with McGraw-Hill.
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