How to Paint Steel Railings and Stairs

To paint metal railings or steel stairs, clean off dirt and grease, remove loose rust and flaking paint back to sound metal, prime bare steel with a rust-inhibitive primer, and finish with two coats of an exterior-grade metal paint. Galvanized and stainless steel can be painted too, but each needs a primer made for that surface. On stairs, treads and landings get a harder, floor-rated finish with a slip-resistant additive, because a smooth painted steel tread can be slippery.

Paint on steel lasts as long as the preparation under it. Most failures, such as peeling, rust bleeding through and blistering, come from skipping steps before the first coat.

Before you start: check the steel and the old paint

Find out what you're painting before you buy anything.

• Bare or painted mild steel. The most common railing and stair material. Rust-inhibitive primer and a metal topcoat work well.
• Hot-dip galvanized steel. Dull grey, sometimes with a spangled pattern. It doesn't need paint to resist rust, but it can be painted for colour with the right preparation and primer.
• Stainless steel. Bright, non-magnetic or weakly magnetic, and usually left unpainted. Paint needs a special primer to bond.
• Wrought or cast iron. Older gates and railings are often iron. Treat them like mild steel.

Then look at the existing coating. If it's sound and well bonded, you can clean, scuff and recoat it. If it's peeling, cracked or rust is lifting it, it has to come off where it has failed.

Lead paint. Many older homes have it. Health Canada says a home built before 1960 probably contains lead-based paint, and one built between 1960 and 1990 may have it on exterior surfaces. If there's any chance, have the paint tested before you disturb it. Health Canada advises against using sanders, heat guns or blowlamps on lead-based paint, since they create toxic dust and fumes, and suggests a chemical stripper paste applied with a brush or hiring an expert.

Surface preparation

This is the step that decides how long the paint lasts.

1. Wash. Scrub with a degreaser or detergent solution to remove dirt, oil and chalky old paint, then rinse and let it dry fully. On exterior railings, road salt residue near driveways and steps has to come off too.
2. Remove loose rust and paint. Wire brushes, scrapers and abrasive pads work for light rust. A drill or grinder with a wire wheel or flap disc is faster on heavier rust. Get back to sound, tightly bonded material.
3. Feather the edges. Sand the edges of remaining paint so the new coating doesn't show a ridge.
4. Scuff glossy paint. Lightly sand sound glossy paint so the new coat can grip.
5. Clean off the dust with a tack cloth or a solvent wipe recommended by the paint maker.

Rust converters turn light surface rust into a stable layer that can be painted, but they aren't a substitute for removing loose and flaking rust. Pitted steel with deep rust, rust between welded joints, or posts rusted through at the base are repairs, not painting jobs. Our post on whether steel railings rust covers where railings usually fail and how to keep them going.

Wear eye protection and gloves for wire brushing and grinding, and a respirator where dust is involved.

Primer: matching it to the steel

Galvanized steel deserves a note. Zinc reacts with some paints, especially ordinary alkyds, and the coating can peel off in sheets. New galvanizing often needs cleaning and a light abrasive sweep or etch before priming. Read the primer's data sheet and follow its preparation instructions exactly.

Apply primer to clean, dry steel the same day you prepare it, before fresh rust starts to form.

Topcoat options

Choose a topcoat rated for metal and for where the railing or stair is:

• Alkyd (oil-based) enamel. A traditional choice for exterior railings and gates. Hard and glossy, slow to dry.
• Direct-to-metal (DTM) acrylic. Water-based, quicker to dry, flexible, and good for exterior work. Some are formulated to go on bare steel, but a primer still helps on rusty steel.
• Two-part epoxy and polyurethane. The toughest system, used for commercial and industrial stairs and high-traffic areas. Epoxy primes and builds thickness, and polyurethane gives colour and UV resistance on top.
• Spray cans. Fine for small touch-ups and intricate pickets, but it takes many light coats to build a durable film.

Two thin finish coats are better than one heavy coat. Paint in dry weather within the temperature range on the can, and avoid painting late in the day when dew can settle on fresh paint.

For railings with many pickets, a small roller or a mitt applicator speeds things up. Brush out runs at the bottom of each picket and check the undersides of top rails, which are easy to miss and where rust often starts.

Painting steel stairs

Steel stairs have two different surfaces: stringers and railings, which get the same treatment as above, and treads and landings, which take foot traffic.

• Use a floor or deck-rated coating on treads. Ordinary railing paint wears quickly underfoot.
• Make treads slip resistant. Article 9.8.9.6 of the 2024 Ontario Building Code requires the finish of treads, landings and ramps to be slip-resistant, among other things. Mixing a slip-resistant aggregate into the finish coat, broadcasting grit into it, or applying slip-resistant strips all help.
• Mind the nosings. The front edge of each tread wears first. Under the same article, stairs other than those serving a single dwelling unit, a house with a secondary suite or a service room also need a colour contrast or distinctive pattern at the leading edge of treads and landings, so keep that contrast when you repaint.
• Plan access. Paint every other tread, or paint one side at a time, so the stair stays usable while coats cure.

Checker plate and grating treads are already textured. On checker plate, a coating that's too thick fills the raised pattern, so keep coats thin. Our guide to types of steel stair treads covers the options, and the steel stairs with wood treads guide covers mixed finishes.

Choosing a colour

The most common railing and stair colour is black, often in a satin or matte finish, because it hides dirt and minor scuffs and suits most houses. Other popular choices are charcoal, dark bronze and white.

Some practical points:

• Dark colours get hot in direct sun, so handrails in full sun can be uncomfortable in summer.
• Gloss shows every flaw in the steel and the prep. Satin is more forgiving.
• White and light colours show rust stains quickly if the coating is damaged.
• Match the hardware. Hinges, post caps and fasteners look better painted with the railing.

New steel: start with the right finish

Repainting is easiest when the original finish was right. For new railings, stairs or gates, hot-dip galvanizing, or galvanizing with paint over it, lasts far longer outdoors than paint alone. Our post on whether structural steel needs paint or galvanizing explains the options, and stainless vs mild steel railings compares the materials.

We fabricate custom steel stairs, railings and gates to your drawings, and we can prime or galvanize to suit; installation is by your installer or contractor. Send us your drawings or measurements for a quote, and see our services for the fabrication work we do.