How to remove rust from metal: scrub, soak or dissolve it

Step by step: how to remove rust from metal

Safety first. Wear gloves and safety glasses: acid rust removers and wire brushes both throw off particles that can hurt your eyes. Never mix vinegar or an acid rust remover with bleach, since the mix releases chlorine gas. Do not sand, wire-wheel or scrape old painted metal (railings, radiators, outdoor furniture made before 1978) until you know the paint is lead-free.

1. 1

   Check what you are dealing with

   Look at the rust. A thin orange film or small spots is surface rust you can scrub off; flaking layers or deep pits need a soak or a rust remover. Find out what the metal is, too: stainless steel, chrome, aluminum and plated metals need gentler methods than plain steel or iron.

2. 2

   Wash off grease and dirt

   Scrub the item with warm water and a few drops of dish soap so rust removers can reach the metal. Dry it with a rag. Oil and grime block vinegar and pastes, and you will get patchy results if you skip this.

3. 3

   Scrub light rust with baking soda

   Mix about 1/4 cup of baking soda with enough water to make a thick paste and rub it onto the rust. Let it sit 15 to 30 minutes, then scrub with a nylon brush, rinsing as you go. On plain steel tools you can rub instead with 0000 steel wool and a few drops of light oil, which lifts the rust without deep scratches.

4. 4

   Soak heavier rust in white vinegar

   Put small parts in a plastic tub and cover them with undiluted white vinegar. Check every hour or two; light rust loosens in 1 to 3 hours and heavy rust can take overnight. Do not leave parts for days, because the acid keeps eating into bare metal once the rust is gone.

5. 5

   Brush off the loosened rust

   Take the part out and scrub with a brass or steel wire brush. The rust should come off as a dark sludge, leaving gray metal. Put stubborn spots back in the vinegar for another hour rather than scrubbing harder.

6. 6

   Rinse and neutralize

   Rinse the part well under running water. To stop any leftover acid, dip it in a solution of about 1 tablespoon of baking soda per quart of water, then rinse again.

7. 7

   Dry it immediately

   Dry the metal with a rag right away, then finish with a hair dryer or a few minutes in the sun. Freshly cleaned bare steel can show a new orange haze, called flash rust, within hours if it stays damp.

8. 8

   Protect the bare metal

   Wipe a thin coat of light machine oil or paste wax onto tools and hardware, buffing off the excess. For outdoor furniture, railings and anything that will be painted, prime with a rust-inhibiting primer and paint. Store tools somewhere dry.

Which rust removal method should you use?

Use the gentlest method that works: scrubbing for light rust, a soak for small parts with heavy rust, and abrasives or a converter for large outdoor pieces. Conservators at the Canadian Conservation Institute start with brushes and fine steel wool with light oil, and warn that strong acid rust strippers can etch some areas down to bare metal.

Cast iron pans need their own method because of the seasoning; see how to remove rust from cast iron.

How to remove rust from stainless steel

Rust on stainless steel is usually a surface stain from iron that landed on it, so a mild oxalic acid cleanser rubbed with the grain removes it. Bar Keepers Friend’s instructions for stainless sinks say to wet the area, apply the cleanser on a non-abrasive sponge, rub in the direction of the grain, and rinse within one minute, then dry with a soft towel.

The same page lists the usual causes: cast iron pans or metal cans left sitting in the sink, steel wool or wire brushes that leave behind particles that rust, and iron in the water. Never use steel wool, a wire brush or chlorine bleach on stainless; all three can make the problem worse. For appliances, see how to clean stainless steel appliances.

What not to use on rusty metal

Most damage comes from using a strong product on the wrong metal. Check the label and the metal before you start.

• Acid rust removers on the wrong surface. CLR’s directions say to dilute it with equal parts warm water, leave it no more than 2 minutes, and keep it off natural stone, brass, copper, aluminum, galvanized metal, painted or coated surfaces, and cast iron.
• Abrasives on chrome or plated metal. Steel wool and wire brushes cut through the thin plating, and the base metal underneath rusts faster.
• Bleach mixed with vinegar or an acid cleaner, which produces chlorine gas.
• Muriatic acid and other strong acids at home. They work fast but can pit the metal and burn skin and lungs.
• Power sanding old paint. The EPA warns that lead-based paint, common in homes built before 1978, becomes a hazard as dust when it is sanded or scraped.

How to keep rust from coming back

Rust needs water and oxygen, so keeping metal dry and coated is what stops it. The Canadian Conservation Institute notes that steady humidity above about 65 percent leads to ongoing rusting, while around 50 percent is safe for most iron.

• Dry tools, knives and garden gear before putting them away, and wipe on a thin coat of oil a few times a year.
• Store tools in a dry spot, not on a damp basement floor, and add a silica gel pack to toolboxes.
• Touch up chips in painted outdoor metal before rust spreads under the paint.
• Never leave cast iron or steel wool sitting in a stainless sink.

Mistakes to avoid

• Leaving parts in vinegar for days, which pits the metal under the rust.
• Skipping the drying step, so the clean metal flash-rusts overnight.
• Using steel wool or a wire brush on stainless steel or chrome.
• Mixing bleach with vinegar or a rust remover.
• Sanding old painted railings or radiators without checking for lead paint.
• Leaving CLR or another acid remover on longer than the label allows.