With the resurgence of steel frame windows in today’s bespoke building designs, an often overlooked detail is colour treatment- and more importantly, rust protection.

While late 40’s Crittal and other steel windows are still going strong, even with high levels of corrosion present they continue to maintain their structural integrity and will continue to do so for the foreseeable future. The difference between these frames from old and new steel variants are many- not only in construction but in final treatments and finishing coats and systems available.

Here we’ll go over the most common types of treatments available and their respective applications. This is a general suitability list that should cover the most common applications. This is by no means a definitive list as there are numerous custom finishes from a range of providers that we can cover in another update.

Internally located items (Powder coated)

By far the most cost-effective application. Specifically for frames that are internal, in non-direct or partial sunlight and not subject to weather.

• Sandblasting – Class 2 is used to remove some mill scale and light rust. Used for more demanding environments.
• Etch primer application – used to improve adhesion with topcoat OR
• Powdercoat Zinc prime (i.e. Dulux Zincsheild)
• Final powder coat – Finishing colour of choice (some powders are applied twice)

Internally located items (wet paint)

Another cost-effective application but requires painting before (preferable) or after installation. Specifically for frames that are internal, in non-direct or partial sunlight and not subject to weather.

• Sandblasting – Class 2 is used to remove some mill scale and light rust. Used for more demanding environments.
• Etch primer application – used to improve adhesion with topcoat OR
• Surface Tolerant High Fill 2 pack Epoxy Primer (i.e. Dulux Durebuild STE)
• Wet paint topcoat designed for ferrous applications (i.e. Dulux LUXATHANE® R, Metalsheild etc.)

Externally located items (Powder coated)

An excellent option that is designed to last. Specifically for frames that are externally located in direct sunlight and subject to all weather.

• Sandblasting – Class 2 is used to remove some mill scale and light rust. Used for more demanding environments.
• Etch primer application – used to improve adhesion with anticorrosion powder primers
• Dulux Zincshield® Powder coat – designed to inhibit rust and adhesion loss on ferrous metals.
• Final powder coat – Finishing colour of choice (some powders are applied twice)

Externally located items (Wet paint)

A great option for the truly bespoke frame finish. Specifically for frames that are externally located in direct sunlight and subject to all weather.

• Sandblasting – Class 2 is used to remove some mill scale and light rust. Used for more demanding environments.
• Etch primer application – used to improve adhesion with undercoat
• Surface Tolerant High Fill 2 pack Epoxy Primer (i.e. Dulux Durebuild STE)
• Zinc rich undercoat – provides protection by sacrificial means
• Wet paint topcoat designed for ferrous applications (i.e. Dulux LUXATHANE® R, Metalsheild etc.)

Externally located items (Galvanizing)

A very strong, budget frienldly option. Specifically for frames that are externally located in direct sunlight and subject to all weather. Care must be taken as the Galvanizing process can deform or bow some thinner materials.

• Sandblasting – Class 2 is used to remove some mill scale and light rust. Used for more demanding environments.
• Galvanizing – Apply a thin coating of zinc to a thicker base metal to seal from external elements
• Surface Tolerant High Fill 2 pack Epoxy Primer (i.e. Dulux Durebuild STE)
• Wet paint topcoat designed for ferrous applications (i.e. Dulux LUXATHANE® R, Metalsheild etc.)

*Wet paint (as with powdercoat) on galvanised steel can have problems with adhesion with no paint manufacturer providing a warranty when painting over this substrate.

Choosing the most appropriate coating is personal preference. Some love the almost flawless finish of powder coatings, others like the character of brushmarks with wet paint application- ultimately, the choice is yours- and you have many!