Home / Stopping Rust on Wrought Iron Gates and Railings

How to Treat and Repaint a Rusting Iron Gate

Iron and steel gates, fences and railings are common on Pasadena properties, from ornamental front gates on Spanish Colonial Revival homes to simple steel driveway gates and stair railings. They are durable, but only as long as their paint holds. Once the coating is chipped or worn through, moisture reaches the metal and rust begins. Rust expands as it forms, lifting the surrounding paint and letting more moisture in, so a small spot can spread under the coating well beyond what is visible. Catching rust early and treating it properly keeps metal work sound and saves the far larger job of repairing corroded parts.

Where rust starts

Rust almost always begins where paint is thinnest or most stressed.

Welds and joints. Welded joints can have rough surfaces and crevices that are hard to coat evenly, and water collects in them.
The bottom of posts. Where posts meet concrete, soil or a planting bed, moisture sits against the metal. Sprinklers make this much worse.
Hinges and latches. Moving parts wear through paint, and hardware attachment points trap moisture.
Horizontal rails and caps. Water sits on top of flat surfaces and in decorative scrollwork.
Chips from impacts. A bump from a car, bin or garden tool breaks the coating and exposes bare metal.
Hollow sections. Tubular steel can rust from inside if water gets into open ends or holes.

Assessing the damage

Surface rust appears as orange or brown discoloration and light flaking. The metal beneath is still solid. This is the stage when repair is simplest. Scale rust forms thicker, layered flakes and can pit the metal. Deep corrosion, where metal has thinned, holes have formed or parts have separated, may need a metal fabricator to cut out and replace sections before painting is worthwhile. Check posts closely at ground level, since rust there can weaken a gate or railing without being obvious from a standing position. Tap suspicious areas with a screwdriver handle. Solid metal rings. Badly corroded metal sounds dull or flakes away.

Look at the concrete and paving around each post as well. Rust-colored staining on a walkway or driveway below a gate usually means water has been running off corroding metal for some time, and the worst of the damage may be hidden at the base where the post enters the footing. If a post moves when you push the gate, or the gate has started to sag and drag, check that post before assuming the hinges are the problem.

Removing rust

Paint over rust fails quickly. Loose rust must come off, and the surface must be clean before primer goes on.

Remove loose paint and rust. Use a wire brush, scraper, sanding pads or a wire wheel on a drill for larger areas. Work until you reach firm, sound paint or bare metal. Feather the edges of the surrounding paint so the new coating does not leave a ridge.
Clean the surface. Wipe away dust and residue. Remove grease, oil and dirt with a suitable cleaner or degreaser, then rinse and let the metal dry completely.
Treat remaining rust if needed. Where tight rust remains in pits or crevices that cannot be fully removed, a rust converter can be applied. These products react with rust to form a stable layer that can be painted. Follow the directions, including the wait time before priming.

On older properties, gates and railings may have many layers of paint, some of which may contain lead if the metalwork dates from before 1978. Wire brushing and grinding lead paint creates hazardous dust and chips. Wet methods and chemical strippers reduce dust. Contain debris on plastic sheeting, keep children and pets away, and clean up thoroughly. Grinding and power sanding of lead paint are especially hazardous and should be avoided or left to professionals trained in lead-safe work.

Priming bare metal

Primer is where most of the rust protection comes from. Prime bare metal promptly after cleaning, before new rust has time to form. Humid mornings can start flash rust on freshly cleaned steel within hours.

Rust-inhibitive primers are designed for ferrous metal and slow the formation of new rust. Use them on bare iron and steel.
Galvanized steel needs a primer made for galvanized surfaces. Some oil-based and alkyd paints do not bond reliably to galvanizing and can peel. Check product labels for compatibility.
Direct-to-metal coatings combine primer and finish in one product. They can be convenient for maintenance, though a separate primer is often recommended over areas of heavy rust repair.

Pay special attention to crevices, weld seams, the undersides of rails and the inside of scrollwork. These are the areas where rust returns first, and they are also where brushing tends to be rushed.

Finish coats

Apply finish paint rated for exterior metal. Two finish coats give better protection than one, especially on edges and corners, where paint tends to pull thin. Brushing works the paint into crevices and textured surfaces more thoroughly than spraying, although spraying can give a smoother finish on flat panels. For ornamental ironwork, a small brush helps reach tight curves.

Metal gets very hot in direct summer sun in Pasadena, and paint applied to hot metal can dry too quickly, blister or fail to level. Paint early in the morning, on overcast days, or when the metal is in shade and cool to the touch. Check the label for temperature limits.

Keeping rust away

Stop the water. Adjust sprinklers so they do not hit posts and rails. Keep soil and mulch away from post bases.
Seal the base. Where posts meet concrete, a sealant around the base can prevent water from pooling in the gap. Make sure water can still drain away.
Cap open tubes. Fit caps on open post tops and tube ends so water does not collect inside.
Adjust the gate. A gate that drags or slams chips its own paint. Keep hinges adjusted and lubricated, and fit a gate stop if needed.
Touch up promptly. Inspect metal work at every spring and fall walk-around. Clean, prime and paint every chip as soon as you see it. A small touch-up now prevents the next round of rust removal.

With rust caught early and bare metal primed promptly, painted iron can stay handsome and structurally sound for a very long time.