How To Prepare Galvanised Metal Surfaces Prior To Painting
When painting galvanized metal surfaces, preparation is everything. Whether you’re working with newly galvanized steel or repainting an existing finish, the success of your coating hinges on how thoroughly the surface is cleaned, treated and primed beforehand.
Proper preparation helps ensure strong adhesion, long‑lasting performance and a finish that looks professional and holds up over time. Read on to find out how to prepare galvanised metal surfaces prior to painting.
When painting galvanized metal surfaces, preparation is everything. Whether you’re working with newly galvanized steel or repainting an existing finish, the success of your coating hinges on how thoroughly the surface is cleaned, treated and primed beforehand.
Proper preparation helps ensure strong adhesion, long‑lasting performance and a finish that looks professional and holds up over time. Read on to find out how to prepare galvanised metal surfaces prior to painting.
New Surfaces
New galvanised metal must be clean, dry and free of contaminants before painting. Oils, greases and similar residues should be removed using a suitable solvent cleaner such as Polycote’s own Solvent Cleaner.
If the surface has a chromate or silicate treatment, this should be removed by an abrasive method – for example using specialist equipment such as shot‑blast machines or surface‑abrasion tools.
Any water‑soluble contaminants should be thoroughly rinsed off with clean water.
New galvanised metal must be clean, dry and free of contaminants before painting. Oils, greases and similar residues should be removed using a suitable solvent cleaner such as Polycote’s own Solvent Cleaner.
If the surface has a chromate or silicate treatment, this should be removed by an abrasive method – for example using specialist equipment such as shot‑blast machines or surface‑abrasion tools.
Any water‑soluble contaminants should be thoroughly rinsed off with clean water.
Previously Painted Surfaces
If you are repainting a galvanised surface, special care is required. For freshly applied galvanising, the surface must be cleaned and abraded very carefully because the new galvanised layer can act like a release agent, preventing good adhesion if simply over‑coated without preparation.
If the existing coating is still well adherent and you are applying a fresh coat purely for appearance purposes, then cleaning and “keying” (i.e., lightly abrading) the existing coating is sufficient to promote good inter‑coat adhesion.
However, if the existing paint layer is flaking or peeling, it is strongly advised to remove the coating completely and restart with a properly prepared substrate.
In cases where galvanising is missing altogether and bare steel is exposed and showing rust, you must treat those areas as bare steel. For more information on preparing ferrous metals head to – How To Prepare A Metal Surface For Paint.
If you are repainting a galvanised surface, special care is required. For freshly applied galvanising, the surface must be cleaned and abraded very carefully because the new galvanised layer can act like a release agent, preventing good adhesion if simply over‑coated without preparation.
If the existing coating is still well adherent and you are applying a fresh coat purely for appearance purposes, then cleaning and “keying” (i.e., lightly abrading) the existing coating is sufficient to promote good inter‑coat adhesion.
However, if the existing paint layer is flaking or peeling, it is strongly advised to remove the coating completely and restart with a properly prepared substrate.
In cases where galvanising is missing altogether and bare steel is exposed and showing rust, you must treat those areas as bare steel. For more information on preparing ferrous metals head to – How To Prepare A Metal Surface For Paint.
Need More Advice on Metal Preparation?
Our technical team are on hand to offer advice and product recommendations on any metal painting projects. Call 01234 846 780 or email [email protected].
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