The Look of Rust Without Compromising Integrity
Painted Rust Finishes vs Real Rust Finishes
The oxidization of steel sees the reaction of iron and oxygen to environmental elements such as moisture, to create a reddish-brown oxide, often known as rust. While this color provides warmth and an appealing visual effect for certain designs, rust represents the degradation of the metal. This is an ongoing process and over time, can consume the metal entirely, completely compromising the metal’s structural integrity.
This finish has gained popularity in modern building design for its rustic or industrial aesthetic. However, a deteriorating surface is not an ideal roof or wall material to protect against the elements. To address this need, different options have been developed including the use of thicker steel products, specialty weathering steel products, and painted finishes that recreate rust aesthetics. So, what are the key differences between naturally rusting products and a painted rust finish?
The lifespan of naturally oxidized products will be dependent on the installed environment and the presence of factors such as moisture. The rate of oxidation can also vary significantly across a singular surface based on factors such as shade and leaf litter, snowfall, and water runoff. By comparison, a painted product will have a consistent finish designed to provide a robust, consistent protective barrier across the whole surface against environmental factors. If the appropriate paint system is selected for the environment, and the roof is cleaned as required (typically a periodic rinse of debris) the color and finish of a painted surface will remain consistent across the surface for many decades.
The other benefit of a painted finish is that it will carry a warranty against finish inconsistencies. Robust products such as ASC Building Products’ Natural Rust can carry robust finish warranties.
Naturally rusting products typically use a thicker base metal to combat the effects of rust. Either they use a thicker base to simply extend the time it takes to corrode the metal or for specialty products such as weathering steel, it features a surface that rusts but forms a barrier preventing the corrosion of the core steel underneath. In either instance, both involve using a thicker and subsequently heavier metal compared to traditional metal roof and wall products.
Outside of the cost of purchasing more material, the thicker base metal can significantly add to the weight of the structure and may require additional building reinforcement or structural planning to ensure it can carry the weight of the additional material. Painted rusted metal roofing and siding uses the same paints and processes as regular metal roof and wall products. This means these painted products are available in the same standard thicknesses and widths as traditional metal products which offer exceptional performance relative to weight.
Naturally oxidized finishes will have greater variability in the finish as the visual patina occurs naturally based on a variable interaction with the broader environment. Printed rust designs will offer variability in the pattern but will be limited by the diameter of the paint roll which applies to the printed design. This means that eventually, the pattern will repeat every three to five feet. Printed designs like ASC Building Products’ Natural Rust have been specially developed to create patterns that blend repeated sections to avoid creating a visible, inauthentic ‘wallpaper’ style effect on a surface. This underpins why specially formulated painted designs do not feature large prominent features as these will create a noticeable pattern that will repeat on a surface.
Naturally oxidized finishes are often selected for their slightly rough surface texture which can add additional appeal to an exterior roof or wall surface. This is created by the surface of the material corroding inconsistently, creating microscopic peaks and valleys on the surface.
Unlike a traditional oxidized finish, a painted rusted finish can take advantage of all the advances in modern paint technology. This means that finishes, such as ASC Building Products’ Natural Rust, use modern ‘Cool’ pigment technology. Cool pigments are designed to better reflect the heat from the sun (infrared radiation), transferring less of the heat to the structure, reducing building cooling costs. These factors are important considerations as part of modern building programs such as LEED or Living Building Challenge.
Naturally oxidized or rusted finishes can create more maintenance headaches compared to a painted rusted finish. Particularly when new and the oxidized surface is unstable, factors such as rainwater can dissolve the rust, washing it off to surrounding areas. For some surfaces, particularly stone and concrete this rust runoff can lead to permanent, unsightly staining. Some weathered steel products may also require treatment or varnish to stabilize the rate of corrosion and prevent further structural degradation. By comparison, a painted metal surface will just need to be periodically rinsed of dirt and organic material accumulation such as leaves, directions for these simply cleans are typically provided in the products finish warranty.
Not everything that’s damaged or rusted should be discarded or replaced. Take, for example, old roofs. However much money you pour into fixing up old roofs, there will come a time when it’s best to simply tear down the old roof and start over by installing a new one. This might be the case if your roofing materials are so badly damaged that it isn’t practical to just replace one of the three layers of the roof on its own.
In summary, it IS possible to attain the look and beauty of a naturally rusted finish, without having to deal with the headaches that come with it. Our Natural Rust metal roofing and siding provides you with the warmth and an appealing visual effect of rust while maintaining its structural integrity for years to come.
At ASC Building Products we specialize in the development of authentically painted metal and rust finishes. To learn more about the painted metal used for metal roofing and siding, visit our Homeowner Center.
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