Warranties and specifications for finishes on architectural aluminum products typically address color fading, chalking, gloss loss and adhesion, but they do not mention corrosion. This is because the warranties are for the finish itself, not the underlying metal where corrosion could take place. Linetec’s finishes can help protect your architectural aluminum from corrosion, even if this is not explicitly stated in our warranty.
Corrosion is the gradual degradation of a substance, often associated with metal, by chemical action. Corrosion may conjure up images of a rusting ship on the seafloor, old machinery left immobile in a field or a pitted Viking-age sword from an archeological dig. These common examples of corrosion involve the oxidation of iron and iron alloys resulting in rust. Rust forms on iron in the presence of water and oxygen then flakes off, exposing the underlying metal and allowing rust to form again.
Aluminum, on the other hand, does not rust in the presence of oxygen and water. Instead, it forms a relatively stable oxidized layer that protects against the metal from further corrosion. In fact, this is how anodize finishes are created; by tightly controlling and enhancing the oxidation process. A correctly applied, properly specified finish can establish a flawless protective layer on architectural aluminum to prevent corrosion.
Under certain conditions, aluminum may progressively corrode in the presence of other chemicals, namely sulfates and chlorine. These chemicals come into contact with architectural aluminum through two main sources: acid rain, such as in urban areas with heavy pollution, and salt spray, such as in coastal climates.
Aluminum is most likely to corrode at flaws and grain boundaries where the oxide layer is inconsistent, such as the edge of a product, a bend or a scratch. When the protective finish is compromised, corrosion can take hold. Minor damage can lead to significant corrosion if moisture that contains chlorine or sulfates collects on exposed aluminum without a pathway to drain or evaporate.
Great care should be taken when working with strong acidic or alkaline substances, like mortar or muriatic acid, which can damage finishes. Metal tools can scratch and gouge finishes. Cleaning of painted and anodized aluminum finishes should be done using mild soap solutions at most, and usually these low-maintenance finishes only require a rinse with clean water.
If the protective finish layer stays whole and intact, it’s more likely that the aluminum also would be protected from corrosion. When selecting a finish for aluminum material that may be exposed to corrosive conditions, specify it to meet the highest performance standards available from the Fenestration and Glazing Industry Alliance (FGIA). For anodize, this is AAMA 611 for Class I anodize. For paint, this is AAMA 2605 for 70% PVDF resin-based architectural coatings.
Linetec’s state-of-the-art equipment, our quality-controlled processes and our associates’ expertise ensure the finishes on your aluminum products will be applied as specified and backed by our long-term warranties. Unless a particular project is in an extreme environment, one should expect our finishes to last several years beyond, and in some cases multiples of, the warranty period.
For best results, remember to specify AAMA 611 or 2605, take care during construction and installation, and regularly clean the material throughout the finished aluminum products’ lifespan.
Please click the links to view our sample paint and anodize warranty coverage. For personalized assistance in selecting finishes for projects in extreme climates and conditions, please contact a Linetec associate serving your region.Contact Us