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How to clean galvanized steel

Galvanized steel can last a lifetime, so it’s expected that it won’t stay looking like new forever. Dirt can build up from everyday mud and grime, as well as from industrial sources. Therefore, you may be wondering how to clean galvanized steel.

While you can clean steel before galvanizing it with shot blasting, the galvanized finish on the steel will be compromised if you try to shot blast it after galvanizing. Fortunately, there are ways of cleaning galvanized steel that don’t damage the coating.

Close up of steel

Cleaning galvanized steel

There are several ways of treating stains or marks on galvanized steel. Cleaning should be conservative at first, becoming more vigorous as needed. This is to ensure you don’t damage the zinc coating.

When cleaning bulk contaminants such as dirt, ordinary soaps can be used. For more adherent contamination or for larger areas, the use of a low-pressure wash with pure water, or alongside proprietary cleaning materials such as car wash fluid, can be effective. The car and truck cleaners are formulated to minimise corrosion on the metallic parts of vehicles so are suitable for use on galvanized steel. However, it is important wash the steel with fresh water afterwards.

Many mild stains (such as those from water ponding and water runs) can be removed with the use of common household ammonia cleansers. Again, be sure to thoroughly rinse the galvanized article with fresh water afterwards.

Finally, do not use any abrasive materials on the steel, as this can wear away the zinc coating achieved from the galvanizing process. It’s best to use a water-based emulsifier; alkaline-based cleaners with a pH of 12 or lower; or organic solvents for cleaning galvanized steel.

After cleaning, rinse the area with clean water and wipe the steel with a soft cloth. Make sure that you fully dry the steel to avoid the formation of wet storage stain on the surface.

Removing cement from steel

During building or renovations, cement and mortar may be dropped onto the galvanized steel. This can be very difficult to remove from the steel once it has hardened. If this occurs, remove the large parts of the deposit as close to the surface as practicable. Oxalic acid can then be used to remove the remaining remnants from the galvanized steel, followed with a thorough rinsing. Other acids are more effective on the mortar or cement, but these can be very damaging on zinc and are not recommended.

How to remove wet storage stain

Wet storage stains, also known as white rust, are common when galvanized surfaces are exposed to moisture (such as rain, dew, or condensation) and there is limited air flow over the surface. Wet storage stains can be prevented by storing galvanized steel in ventilated areas away from moisture.

While it’s best to prevent white rust rather than remove it, you can clean it by using a diluted acidic or ammonia solution, followed by a thorough rinsing with clean water.

Wet storage stains on steel

How to touch up galvanized steel

Over time, there may be some areas that lose their galvanized coating. This can happen if you clean your steel incorrectly, or through gradual damage that builds up from everyday movement and impact. Fortunately, patches of damaged steel can be touched up with a zinc spray.

Zinc sprays contain condensed amounts of zinc that you can spray onto affected areas, without having to re-galvanize the whole fabrication. This saves you time and money compared to re-galvanizing the whole fabrication. It also helps extend the lifespan of steel as it prevents rust from building up inside the damaged areas, which may save you from needing to rebuild the fabrication from scratch.

One brand of zinc spray you can use is Galvsafe Zinc Spray. Galvsafe Zinc Spray is safe to paint and powder coat over, making touching up your steel easy. The Zinc Spray also colour-matches steel, so it blends in seamlessly and keeps the fabrication looking like new. It’s ideal to use after cleaning your galvanized steel to help maintain its lifespan. Order yours today by contacting your nearest Joseph Ash Galvanizing site.

If you have any questions about cleaning your galvanized steel, get in touch with your local galvanizer for advice.

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