Galvanised steel is coated with a sacrificial layer of zinc, which alloys to the bare steel surface to provide a physical barrier against corrosion.
Over time, as the zinc coating suffers damage such as scratches and light gouges, the steel underneath remains unaffected – and if you work on the steel, for example by drilling or cutting, the sacrificial corrosion of the zinc continues to protect the metal beneath.
Painting steel is another way to provide surface protection, again by adding an exterior coat to the steel to insulate it against corrosion.
So, can you paint galvanised steel, and do you need to?
Do you need to paint galvanised steel?
First of all, let’s answer the question of whether you need to paint galvanised steel. The simple answer is no, you don’t need to.
Galvanised steel is protected against corrosion, and galvanising can be carried out quickly and cheaply by submerging the steel in molten zinc.
Unlike paint, sacrificial zinc will continue to protect the steel even after cutting and drilling, whereas the exposed unpainted surfaces may be at risk of corrosion.
Repainting steel structures can also be quite time-consuming, and is likely to be necessary if the steel is not galvanised.
However, painting galvanised steel for aesthetic purposes is absolutely fine and should have no ill effects on the protection given to the steel by the zinc galvanisation.
How to paint galvanised steel
To properly paint galvanised steel, it’s best to prepare the surface for the best adhesion with the paint, for a long-lasting paint job that will not need maintenance or repainting in the near future.
You can prepare the surface in several ways, for example:
- Applying a liquid primer
- Blasting with a powder
- Surface abrasion with pads or brushes
You should also use a paint that is designed to be used on galvanised steel. High-build epoxy paints, vinyl co-polymers and water-based polyurethanes are all good options, and the manufacturer should provide recommendations about application.
James Dunkerley Steel painting services
James Dunkerley Steels offer painting services for galvanised steel and untreated steel alike, and we can make sure your steel sections have the desired aesthetic ahead of delivery.
We also offer steel galvanising services – so however you choose to protect your structural steel, we can carry out the necessary preparation work.
To learn about our steel fabrication and other services, please contact James Dunkerley Steels today and our team will be happy to talk you through our services and which might be most appropriate for you.
