Two-Pack Epoxy Paint: When Commercial Steel, Plant and Signage Needs It

By Alex Dzissah, Founder, AKD Painting

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

Two-pack epoxy paint is a coating that cures by chemical reaction between a resin and a hardener mixed on site, rather than by drying in air. Over prepared steel it forms a hard, bonded film that resists corrosion, impact and washdown far better than single-pack enamel. That is why plant, structural steel and signage frames get coated with it.

What is two-pack epoxy paint, and how is it different from ordinary paint?

Ordinary paint dries, while a two-pack coating cures. Single-pack acrylics and enamels form a film as solvent or water leaves them, and that film stays chemically much the same as what came out of the tin. A two-pack epoxy arrives as a resin and a hardener that react once mixed, producing a cross-linked film chemically bonded to the primer under it.

The difference shows up under abuse. A cured epoxy film resists abrasion, impact, oils and washdown detergents, and it holds a barrier against moisture instead of letting it creep to the steel. That creep is what starts almost every rust problem on a commercial site.

Mixed material has a limited working window before it hardens in the pot, so it gets batched to the area being coated rather than made up in bulk. Epoxies also chalk under sustained ultraviolet light, so anything in full sun and on public view gets a UV-stable topcoat over the epoxy rather than the epoxy left bare.

Standard exterior wall paints are built for render, masonry and timber, and our comparison of the main exterior brands covers those surfaces. Steel that gets hit, wetted and washed down sits outside what they are formulated for, which is where Dulux Protective Coatings comes in.

Which assets on a commercial site actually need it?

The ones that get wet, get hit, or get cleaned with chemicals. On most Sydney sites that is a short list.

Plant and equipment sit at the top. Compactors, hoppers, cages and bin surrounds hold water in every seam and get knocked by trucks daily. Structural steel comes next, and the risk concentrates at connections, base plates and anywhere two members meet, because those are the places water sits and nobody inspects. External stairs and balustrades wear from contact rather than weather, and bollards and guard rails take direct impact by design.

Signage and light poles are the ones facility managers most often under-specify. A pylon frame is structural steel holding a branded face, and when it rusts, the rust tracks out of the fixings and streaks down the sign years before the frame becomes a structural concern.

Plenty of a building needs no two-pack at all. Walls, ceilings and retail interiors are a different specification, and back-of-house corridors and stairwells sit in our guide to paint for high-traffic areas. Roof sheeting is its own decision, in the roof painting guide. Apartment common areas follow the strata process.

What should the scope say about surface preparation?

Preparation decides how long the system lasts, so it belongs in the written scope, not in a verbal assurance. A coating applied over mill scale, loose rust or a chalky old film is stuck to the failure, not to the steel. Four things belong in writing.

The cleanliness standard. Metal surface preparation is covered by Australian Standard AS 1627, and specifications commonly name a grade, such as St 3 for thorough power tool cleaning or Sa 2.5 for abrasive blasting. Naming the grade removes the argument about how far back the rust was taken.

The system, coat by coat. Primer and topcoat listed as a matched system from one manufacturer, with the dry film thickness nominated per coat. Thickness is measurable with a gauge afterwards, which makes it worth naming.

The conditions for application. Two-pack materials cure slowly in cold weather and should not go onto steel close to the dew point, because condensation ruins adhesion. A winter programme in Sydney needs the working window written in.

Who fixes what, and for how long. AKD quotes the preparation and the system in writing, itemised per asset, and the work carries a 5-year written workmanship warranty, backed by Dulux Protective Coatings.

How long is the asset out of service?

Less time than most facility managers expect, though full cure runs longer than handling hardness. A two-pack topcoat is generally hard enough to handle within about a day in mild conditions, and reaches full chemical resistance over roughly a week. Cold weather stretches both figures.

Sequencing matters more than the cure. Preparation is the noisy, dusty stage, worth scheduling around trading hours or shift changes. Coating is quieter and faster. Plant is often done in rotation so part of the fleet stays in service while the rest is coated. Our guide to minimising downtime on commercial sites covers the scheduling side across offices and retail.

What makes a coating system fail early?

Almost always preparation, and after that, the wrong system for the exposure. These four account for most of what we get called out to inspect.

Rust left under the coating keeps working, and the film blisters in rings around each spot inside a year. Zinc-coated steel painted without the right primer lets go in sheets, a different problem with a different fix, covered in our guide to paint for galvanised steel. Recoating outside the manufacturer’s window without abrading the previous coat leaves two layers that never bond. And a single-pack enamel put on a bollard because it was quicker is back at bare metal before the next inspection.

Exposure changes the answer across Sydney. A workshop in Marrickville or a light industrial unit in Camperdown is a milder environment than a site on the water. Retail steel along the strips in Leichhardt and Ashfield deals with traffic grime and impact rather than salt. Anything within a few streets of open water carries airborne salt, which shifts the specification upward.

What did this look like on a real site?

At IKEA Rhodes, the waste compactor fleet had surface rust spreading across roofs, doors and panels. The crew ground the corrosion back to sound metal, treated the affected areas, pressure washed, then primed and finished the units in a Dulux Protective Coatings two-pack system. They went back into service with a sealed, cleanable surface.

The full sequence, with before and after photographs, is on the IKEA Rhodes project page. Compactors are about as hard on a coating as commercial steel gets, sitting outdoors year round and being washed down between knocks.

Frequently asked questions

What is the difference between two-pack epoxy and single-pack enamel?

Single-pack enamel forms a film as it dries and stays chemically much the same as what came out of the tin. Two-pack epoxy is mixed from a resin and a hardener that react together and cure into a cross-linked film bonded to the primer beneath. The cured film resists impact, abrasion, oils and detergents in a way enamel does not, which is why it is used on plant and structural steel rather than on walls.

Can two-pack epoxy be used outdoors in full sun?

Yes, though usually not as the visible surface. Epoxies chalk and lose gloss under sustained ultraviolet light, so on anything exposed and on public view, such as signage frames, pylon signs and light poles, the epoxy does the protection and a UV-stable topcoat goes over it to hold the colour and finish.

Do you have to blast the steel, or is grinding enough?

It depends on the condition of the metal and what the coating manufacturer specifies. Thorough power tool cleaning by grinding, wire brushing and scraping is enough on many assets with localised corrosion, and it was the method used on the compactor fleet at IKEA Rhodes. Heavy mill scale or widespread pitting calls for abrasive blasting. The scope should name the grade required so there is no ambiguity.

How long before the equipment goes back into service?

A two-pack topcoat is generally hard enough to handle within about a day in mild conditions and reaches full chemical resistance over roughly a week. Cold weather extends both. On multi-unit jobs the work is usually staged in rotation so part of the fleet keeps operating while the rest is coated.

Can a two-pack system go over the existing coating?

Sometimes, and only after testing. Sound, well-adhered coatings can be abraded and overcoated if the new system is compatible with what is already there. Anything loose, chalky or rusting underneath has to come off first, because a new coating is only as sound as the layer it is stuck to.

Does signage need a different system to structural steel?

The protection is similar but the finish is not. Both want a properly prepared surface and an anti-corrosive primer. Signage carries the extra requirement of colour accuracy and gloss retention, so it gets a UV-stable topcoat and the colour is matched to the brand standard before anything is applied.

Get steel and plant on your site assessed

AKD Painting has worked across Sydney since 2013 and handles protective coatings for businesses alongside commercial and residential repainting, including the compactor fleet at IKEA Rhodes and painting at the Qantas head office. We are Dulux Accredited and rated 5.0 stars across more than 130 Google reviews.

Call 0474 854 369 or request a quote for a site walk and a written scope. We are based in Summer Hill NSW 2131 and work across the Inner West and the wider Sydney metro area. See our industrial painting and protective coatings service, or our commercial painting work.