Painting galvanised steel can be tricky if you don’t follow the correct process and when done wrong, it’s one of the most common causes of paint failure on metal.
In this guide, we’ll walk you through why standard paints often fail on galvanised surfaces, what you need to do to ensure proper adhesion and which systems work best - including our specialist direct-to-galv coatings.
Why Most Paints Fail on Galvanised Steel
Galvanised steel is coated with a layer of zinc to protect it from corrosion. While this makes it highly rust-resistant, it also makes it difficult for standard paints to adhere properly.
One of the biggest issues is saponification - a chemical reaction that occurs when alkyd-based or oil-based paints come into contact with zinc. The result? The paint bubbles, lifts and eventually peels off, often within weeks.
First Step: Degreasing is Essential
Galvanised steel often comes with an oily surface film known as "mill oil" or handling grease. If not properly removed, this will stop any coating - even specialist ones, from bonding correctly.
Always start with a powerful degreaser such as Zinsser Universal Cleaner Degreaser or Xylene for tougher contamination. Apply using a cloth or pad, then rinse and allow to fully dry before painting.
Not All Galvanised Steel is Bare
It’s common for customers to say they’re painting galvanised steel - when it’s already been painted. If the surface has an existing coating, then you’re not painting galvanised steel, you’re painting paint.
That matters because:
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You’ll need to test compatibility with the previous coating
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You may need to abrade or strip back the old paint
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A direct-to-galv product won't be suitable if it's already painted
Always assess the surface first.
Methods for Painting Galvanised Steel
There’s no one-size-fits-all method - but here are the main ways professionals paint galvanised steel successfully:
1. Adhesion Primers
Use a primer specifically designed for non-ferrous metals and galvanised surfaces.
Our recommendation: AndCoat UltraGrip Adhesion Primer
These primers chemically bond to the zinc, providing a stable base for topcoats. Let the primer fully cure before applying a finish coat.
2. Etching the Surface
Also known as T-Wash, this involves using an acid-based treatment to slightly etch the zinc surface. This creates a roughened, reactive surface for primers or topcoats to grab onto. Coo-Var Mordant Solution
Important: rinse thoroughly and dry before moving to the next step.
3. Mechanical Abrasion
Lightly sanding or wire-brushing the surface is a simple method that improves adhesion.
Use this method on older galvanised steel that may have oxidised (white rust).
This can also be combined with a primer if additional corrosion protection is needed.
4. Use a Direct-to-Galv Paint System
We manufacture, stock and tint a specialist modified vinyl acrylic coating that are engineered to bond directly to galvanised steel, with no need for a primer or acid etch.
These are ideal for railings, gates, ducting, cladding and fencing where speed and ease of application matter.
Do You Need an Anti-Corrosive Primer?
Not always.
Since galvanising already provides excellent corrosion resistance through the zinc coating, you don’t necessarily need an anti-corrosive primer unless:
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The galvanising is old or damaged
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You’re painting cut edges or welds
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The environment is marine or high-corrosive
In many cases, a bonding primer or direct-to-galv system will give more than enough protection.
High Zinc Galv Paint – Protection That Mimics Galvanising
If you’re looking to restore or replicate the appearance of galvanised steel – especially on welds, repairs or cut edges – high zinc content paints are a smart solution.
These coatings, often referred to as cold galvanising paints, contain a high percentage of zinc dust in the formulation. Once applied, they provide cathodic protection similar to that of hot-dip galvanising, helping prevent rust from forming even if the surface is scratched.
They can be applied directly to bare steel or galvanised metal and offer:
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Long-term corrosion protection
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A matt or metallic finish similar to galvanised steel
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Compatibility with overcoating systems if desired
Ideal for structural steelwork, fencing, trailers and on-site repairs, these zinc-rich paints offer a cost-effective and easy-to-apply alternative to re-galvanising.
Tools & Materials Checklist
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Degreaser (essential)
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Clean rags or Scotch pads
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Abrasives or wire brush (optional)
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Adhesion primer or direct-to-galv coating
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Appropriate topcoat (if using a two-coat system)
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PPE: gloves, eye protection and mask when etching
Final Tips
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Always read the product TDS (Technical Data Sheet) before application
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Don’t apply coatings in cold, damp or humid conditions - it will affect cure and adhesion
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Check compatibility if painting over existing coatings
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Apply test patches if unsure
Shop Specialist Coatings for Galvanised Steel
Whether you need a fast-drying direct-to-galv system, a long-life finish for external cladding, or want to replicate new galvanised, our technical team can help you choose the right system.
