Paint for Galvanised Steel: What Stops Rust on Balustrades, Gates and Pergolas

By Alex Dzissah, Founder, AKD Painting

Updated August 2026. By Alex Dzissah, NSW Painting Licence 330882C.

Paint fails on galvanised steel because the zinc surface is too smooth and too reactive for ordinary house paint to grip. Galvanised balustrades, gates and pergola posts need an etch or galvanised-iron primer over a clean, dulled surface. Where salt air is in play, a Dulux Protective Coatings system replaces the standard exterior one.

Why does paint keep peeling off galvanised steel?

Because galvanising is a zinc coating, and zinc is both slippery and chemically active. Two separate things go wrong. The surface of new galvanised steel is hard and smooth, so there is nothing for a coating to key into. And zinc reacts with oil-based and alkyd paints, breaking the binder into a soapy layer that lets go of the metal underneath. The paint can look sound for months, then come away in sheets.

This is why a galvanised gate painted with leftover wall paint almost always fails, and the same gate primed properly stays sound for years. The missing step is the primer.

Older galvanised steel fails for a different reason. After a few years outside, zinc oxidises into a loose white powder. That powder has to be washed and sanded off, because anything painted over it is stuck to dust rather than metal.

How do you tell which metal you actually have?

Galvanised steel is dull silver grey with a faint crystal pattern, mild steel rusts orange, and cast iron is thick, dark and often decorative. The distinction matters because each takes a different primer.

On most Inner West homes the galvanised items are the balustrades, side gates, pergola and carport posts, garage door frames, and the fixings holding it together. Mild and structural steel turns up as posts, beams and the lintels over window and door openings in brick homes. Cast and wrought iron is the heritage material: lacework, palisade fencing and verandah posts on Victorian and Federation houses.

Aluminium window and door frames are a separate job, usually powder coated from the factory, and we assess those individually.

What primer goes on galvanised steel?

A primer made specifically for galvanised iron, applied over a surface that has been degreased and dulled. Never a straight oil-based enamel, which reacts with the zinc, and never a general-purpose wall primer, which has no grip on it.

The preparation matters as much as the product. Galvanised steel arrives from the factory with an oily residue, so it gets degreased first, then dulled by light abrasion or an etching solution so the primer has something to bite. The topcoat follows within the recoat window on the tin.

There is a free option if you are not in a hurry. New galvanised steel left bare for around six months weathers on its own, losing the mill finish and the surface oils, and it will accept a primer far more readily after that. That suits a new balustrade, though it does not help metal that is already rusting.

How do you paint metal that has already rusted?

You take the rust off mechanically, back to sound metal, and prime the same day. Grinding, wire brushing and scraping remove the scale. Rust that is only brushed at the surface keeps working underneath, and the new coating blisters in rings around each spot within a year.

Bare steel starts oxidising again within hours in Sydney humidity, so the gap between preparation and primer stays short. On the compactor fleet at IKEA Rhodes the sequence ran as one operation: grind the corrosion back, treat the affected areas, pressure wash, then prime and coat. The same discipline applies to a rusting balustrade, at a smaller scale.

Painting over deep rust hides it for a season and costs more to put right afterwards.

When is a standard exterior system enough, and when do you need a protective coating?

Standard exterior paint is fine for metal on a sheltered inland home, and not enough for metal that sits in salt air or gets knocked. Standard exterior wall paints are formulated for walls, timber and render. Our comparison of the main exterior brands covers what each does well on those surfaces.

Metal asks for something different. Dulux Protective Coatings is the industrial side of Dulux: coatings built for bridges, plant and structural steel. Over properly prepared metal they cure into a hard, bonded film that holds up against corrosion, impact and weather in a way a house paint cannot. It is the same class of system we put on the IKEA compactors, and it scales down to a residential gate or pergola. The commercial end of the same range is covered in our guide to two-pack epoxy on commercial steel, plant and signage.

The practical test is exposure. If the metalwork has been repainted twice in five years and rust keeps returning through it, the coating class is wrong for the conditions, and that is the point to change it rather than repeat the cycle.

Which parts of an Inner West home rust first?

Balustrades, gates and steel lintels, in that order, and fastest on the streets closest to open water. Balustrades and handrails cop rain, hands and salt at once, and their welds hold water long after the flat faces have dried. Gates fail at the hinge side where the coating gets chipped.

Steel lintels cause the most expensive damage. In brick homes the lintel is the steel bar carrying the brickwork over a window or door. When it corrodes, the rust takes up many times the volume of the steel it came from, and that expansion pushes the brick courses above the opening apart. The cracking often gets blamed on ground movement when the lintel is the cause.

Exposure changes the timeline sharply across the area. Metalwork on a water-facing home in Drummoyne, Balmain or Rozelle carries a load of airborne salt that identical metal in Summer Hill or Leichhardt never sees. Around Five Dock and the bay it sits in between. For the whole-house case on a water-facing property, our guide to painting waterfront homes covers the full exterior rather than just the metal, and the Balmain exterior guide deals with original cast iron lacework on heritage terraces.

Two related surfaces are covered elsewhere. Metal roofing is its own decision and is dealt with in our roof painting guide. Timber decks, pergolas and fences are a different material with different products, covered in the deck and fence guide.

Frequently asked questions

Can you paint straight onto new galvanised steel?

Not with ordinary house paint. New galvanised steel is smooth and carries a light oily residue from manufacture, so the surface has to be degreased and dulled first, then primed with a product made for galvanised iron. The other option is to leave the steel bare for around six months so it weathers naturally, which makes it much easier to prime afterwards.

Why does my galvanised gate keep peeling no matter how often I repaint it?

Almost always because a primer for galvanised iron was never used. Standard acrylic has nothing to key into on zinc, and oil-based enamel reacts with the zinc and turns the binder soapy where the two meet. Each repaint fails at the same layer. The fix is to strip back to the metal, prepare it properly and prime it once with the right product.

Do I have to remove all the rust before painting?

All the loose and flaking rust, yes. It comes off mechanically, by grinding, wire brushing or scraping, back to sound metal, and the primer goes on the same day because bare steel starts oxidising again within hours. Rust converters are useful on light surface corrosion in awkward corners, but they do not replace taking the heavy scale off.

Is a protective coating worth it on a house, or is it only for industrial sites?

It is worth it where the metal keeps failing. If a balustrade, gate or pergola frame near the water has been repainted twice in five years and rust keeps coming through, a protective system breaks that cycle instead of repeating it. On sheltered metalwork away from the water, a properly primed standard exterior system is usually enough.

Can the metalwork be done at the same time as the rest of the house?

Yes, and it is the sensible way to do it. Access is already set up, and the metal preparation happens alongside the other surfaces rather than as a separate visit later. The metalwork is itemised on its own line so you can see what the coating and the preparation cost against the rest of the scope.

What causes the rust stains running down my brickwork?

Usually a corroding steel lintel over the window or door, or rusting fixings and wall ties. The stain is iron oxide washing down the face of the brick. It is worth investigating rather than just cleaning off, because a lintel that keeps corroding expands and eventually cracks the brick courses sitting above the opening.

Get a quote for the metalwork on your home

AKD Painting has worked across Sydney since 2013 and handles metalwork on homes as well as protective coatings for businesses, including the compactor fleet at IKEA Rhodes and painting at the Qantas head office. We are Dulux Accredited, rated 5.0 stars across more than 130 Google reviews, and metal work carries a 5-year written workmanship warranty, backed by Dulux Protective Coatings.

Call 0474 854 369 or request a quote. We are based in Summer Hill NSW 2131 and work across the Inner West and the wider Sydney metro area.