You’re surrounded by tools and machines made out of steel. And when the coatings on those products crack, rust starts to bloom and the battle is on. You can attack rust early and nip it in the bud, or you can wait until you have a full-blown war on your hands. The choice is yours. Either way you’ll need a battle plan and a complete list of weapons at your disposal. And that’s why we’re going to show you the five ways to defeat rust—three methods to remove it and two steps to prevent it from coming back.
Grind, sand or scour off the rust
If you’re not into chemicals and you want to remove the paint along with the rust, use a power tool like a grinder, sander, oscillating tool or drill. A grinder fitted with a stripping disc, grinding wheel, fiber or flap disc makes quick work of heavy rust on large objects. But keep the tool moving so you don’t gouge the metal. For smaller jobs, use a traditional sander. To get into small areas, use a “mouse” sander or an oscillating tool with a carbide rasp or sanding pad attachment.
Whichever tool you choose, always start with the coarsest abrasive to get rid of the rust and pockmarks. Once the rust is gone, switch to a finer grit to smooth out the swirls and grooves caused by the coarse grit. For the smoothest paint job, finish sanding with 400-grit wet/dry paper.
Remove rust with powerful chemicals...
The old standby rust remover chemicals contain either phosphoric or hydrochloric acid to dissolve the rust. They’re harsh chemicals that give off some pretty intense fumes, so suit up with rubber gloves, goggles and a respirator. Find them in the paint department at any home center. You’ll also need an old paintbrush, a waste tub, a 3-in. putty knife and rags.
Apply the chemicals with the paintbrush and wait the recommended time for the chemicals to work. Then scrape off the liquefied rust. You won’t get it all in a single step—count on multiple applications to completely remove heavy rust buildup. Consider a gel formula when removing rust on vertical surfaces. It’ll cling better and result in less runoff.
...or with safer and gentler chemicals
Try one of the newer nontoxic and acid-free soaking solutions shown here. I bought this gallon of Evapo-Rust at an auto parts store. These chemicals dissolve rust through the process of “selective chelation.” I don’t know what that is, but I can tell you it works if you’re patient.
Start by cleaning off any oil or grease. Then dunk the rusted part in a tub of solution. The product says it’ll dissolve rust in either 30 minutes or overnight. Based on my experience, you’d better plan on overnight, because even this minimally rusted C-clamp took that long. Keep in mind that this is a soaking solution—you can’t paint it on or spray it on. So, if you’ve got a large object, you’re going to need a lot of solution, and that’s going to cost a lot more.
I’ve written before about how much I love using Acid Magic for removing rust from sinks, toilets and showers. Well, I obviously have lots of iron in my well water—the latest evidence is that all our ground-level windows had a reddish tint from the sprinklers. I had no idea how to remove it until I thought of Acid Magic again.
I brushed it on with a paintbrush and the rust instantly dissolved and ran down the glass. If you have other mineral deposits in your water, I’m certain it’d take care of them, too.
-Travis Larson, Senior Editor
or at Amazon through our affiliate program.
Convert it—it’s the easiest method
If you can live with the look of a rough or pockmarked finish, rust converter can save you a lot of time. It kills the rust, prevents its spread and dries into a ready-to-paint primer. Buy it at any home center or auto parts store. Start by removing any flaking paint and rusty dust with a wire brush. Then either spray on the converter or apply it with a disposable paintbrush. Let it dry for the recommended time. Even though the label says you can paint after it dries into a primer coat, I recommend spraying on a real primer. Then paint. Apply a second coat of converter if you’re not going to paint. Don’t return leftover converter to the bottle—it will contaminate the rest. Toss it in the trash, along with the brush.
Three Ways to Remove Rust
Grind, sand or scour off the rust
Pros: No pockmarks and a smooth finish prior to painting. Complete project in a day. No waiting for chemicals to work.
Cons: Dirty, dusty, hard work. Requires power tools and lots of elbow grease.
Convert the rust
Pros: Easiest way to stop rust and prime in one operation. Less expensive than chemical or mechanical methods for removing rust.
Cons: Leaves a rough or pockmarked finish that’ll show after you paint. May not inhibit rust as long as traditional removal, priming and painting.
Remove rust with chemicals
Pros: Soaking removers can do all the work for you if the item is small enough. Spray removers greatly reduce the grunt work, but they require several applications and some scraping.
Cons: Long wait times for the liquid removers to do their job. Makes a huge mess. Soaking removers are expensive and can be used only on small items. The surface will still be pockmarked after the rust is gone.
Tip: Don’t think you can spray rust-inhibiting paint onto a rusty surface and get good results. The rust will bleed right through the paint and ruin your new paint job. You have to deal with the rust with one of the methods we show here. There’s just no way around it.
Prime before painting
No matter how you get the rust off, you still have to prime before painting. If the surface is smooth, simply spray on a metal primer (light gray for light-colored paints, black for darker paints). However, if the surface still has pockmarks, swirls or scratches, use a “sandable” or “filler” primer to fill in the depressions.
Surface preparation prior to priming is critical, especially if there’s any old paint left on the item. Clean the surface with a wax-removing solvent (buy at any auto parts store) and a tack cloth.
Pick a high-quality paint
After all the nasty prep work, why risk another bout of rust by using cheap paint? Inexpensive paint contains less pigment, fewer resin binders and no rust inhibitors. Spend a few extra bucks on a premium rust-inhibiting paint. It will contain zinc additives that provide an extra measure of protection against future rust.
Brushing usually provides a better paint bond than spraying, but it leaves brushstrokes in the finish. However, spraying is tricky and if you stay in one spot too long, you can wind up with paint sag marks in the finish.
Whichever painting method you choose, seal the newly painted item with a clear topcoat. That’ll add to the gloss and dramatically increase the life of the paint by reducing paint oxidation.