We take a look at zinc metal spray coatings - one of the best solutions for protecting steel from rust and corrosion.
What Is a Zinc Coating?
A zinc coating is a layer of zinc that’s added to the surface of steel. It stops rust from forming. This is because zinc reacts with moisture and oxygen before the steel does. In other words, zinc sacrifices itself to protect the steel.
This process is called cathodic protection. It means the zinc will corrode first, saving the steel underneath.
Why Use Zinc on Steel?
Barrier protection – The zinc layer stops water, oxygen and other elements from reaching the steel.
Cathodic protection – Zinc is more reactive than steel. If the coating is scratched, the zinc will corrode first. This protects the steel underneath.
This double layer of defence makes zinc a very reliable coating solution.
How is it Applied?
Zinc coatings are sprayed onto steel using a process called thermal spraying. The zinc acts as a shield, keeping moisture and air away from the steel.
It all starts with surface preparation. The steel must be clean and roughened to help the zinc stick. This is often done using grit blasting, which removes rust, paint, and oil.
Next, a spray gun melts and sprays the zinc onto the surface. As the molten zinc hits the steel, it forms a thin, even layer. The coating usually ranges from 50 to 200 microns thick, depending on the need.
Once the coating is on, the surface may be sealed or painted, adding even more protection.
What Equipment Is Used to Spray Zinc?
At Metallisation, we offer a range of thermal spray systems for zinc coatings. These include:
Arc Spray Systems – Using electricity to melt zinc wire.
Flame Spray Systems – Using a gas flame to melt zinc wire or powder.
Each system has its own benefits, depending on the job. Arc spray is fast and great for large areas. Flame spray is more portable, so it’s perfect for small or hard-to-reach places.
Is Training Required?
Yes – but it’s not complicated. Operators should be trained to prepare the surface correctly, set up the equipment, and apply the coating evenly. At Metallisation, we offer a range of training courses to help get the most out of using our thermal spray equipment, along with expert support.
How Long Do Zinc Coatings Last?
Zinc spray coatings can protect steel for over 20 years, even in tough environments.
For example, studies from the International Zinc Association show that in rural areas, zinc can protect steel for up to 40 years. In marine environments, it lasts about 15 to 25 years, depending on the thickness.
With regular checks and maintenance, the protection can last even longer.
Common Uses of Zinc Spray Coatings
You’ll find zinc coatings almost everywhere steel is used outdoors. Here are just a few examples:
Bridges and Infrastructure
Zinc coatings help to protect steel bridges from rain, salt and pollution.
Buildings and Steelwork
From railings to support beams, many steel parts in buildings use zinc spray for long lasting protection.
Marine and Offshore
Ships, ports and oil rigs deal with saltwater every day. Zinc coating helps stop rust in these harsh settings.
Pipelines and Storage Tanks
Underground and above ground tanks and pipes benefit hugely from zinc coatings.
Is Zinc Spray Better Than Galvanising?
Yes, for many jobs, zinc spraying has key advantages over hot dip galvanising:
It’s completed on-site or in a workshop – No need to dip large or fixed structures.
No size limits – Spray coating works on big or awkwardly shaped items.
No heat distortion – Steel doesn’t get too hot, so there’s less risk of warping.
Better grip for paint – Zinc spray has a rough surface. Paint sticks well, which adds extra protection.
Is Zinc Coating Environmentally Friendly?
A zinc coating is a layer of zinc that’s added to the surface of steel. It stops rust from forming. This is because zinc reacts with moisture and oxygen before the steel does. In other words, zinc sacrifices itself to protect the steel.
This process is called cathodic protection. It means the zinc will corrode first, saving the steel underneath.
What Does a Zinc Coated Surface Look Like?
Right after spraying, it looks dull grey or silver. Over time, it may darken or form a matte finish. Some people paint over it for a smoother look or to match a colour scheme.
The coating can be left bare or sealed, depending on the final use.
What Does It Look Like Arc Sprayed?
What Does It Look Like Flame Sprayed?
Ready to Protect Your Steel?
At Metallisation, we’ve helped companies around the world protect steel for over 100 years. We’re able to supply the right tools, training and support for every zinc spraying job. Whether you’re starting a new project, need to repair an old structure, or are just after some advice – we’re here to help.