The Finishing Touch: Updated Standards Ensure Long-Term Durability and Appearance

By Rich Rinka

Since its inception, AAMA/WDMA/CSA 101/I.S.2/A440 North American Fenestration Standard/Specification for doors, windows and skylights (NAFS) has defined the basis for quality assurance of completely fabricated door and window units. It provides material-neutral industry consensus standards for basic framing materials, such as aluminum, fiberglass, vinyl and wood. Finishes provide another layer of protection, while also creating an enduring appearance for all of these materials. When applied, they also must meet the appropriate standard referenced within NAFS.

For aluminum, fiberglass and vinyl substrates, standards are organized in a “good, better, best” style, including basic performance, high-performance and superior performance, with increasingly stringent criteria. This hierarchy allows specifiers to choose appropriate finishes which meet a project’s cost, performance and long-term durability targets.

Weighing the Variables

The finishes standards describe laboratory test methods and performance criteria for various parameters shown to be critical to the performance of factory-applied organic (hydrocarbon-based) coatings. These include acrylics, polyesters, siliconized polyesters and various types of fluoropolymers, on various profile substrates. For some of these parameters, the minimum performance requirements are the same for all three levels. For others, time of exposure to the test condition lengthens and/or the permitted latitude of results narrows. Additional stressors are added for higher-performing coatings in some cases as well. One example of this is outdoor weathering tests to determine resistance to ultraviolet (UV) light, which might chemically break down the components of the finish, resulting in chalking or fading.

All of the finishes standards refer to the latest ASTM test methods or specifications for key generic properties such as adhesion to the substrate (e.g., ASTM D3330, D3359 or D5179) and color retention under exposure to accelerated outdoor weathering (e.g., ASTM D2244, or D4726).

Finishes for Profiles

For coatings on aluminum profiles, the “good, better, best” triumvirate is addressed by AAMA 2603, 2604 and 2605, an FGIA series of technical documents which also include coatings of increasing minimum thicknesses. All three standards test for color uniformity, specular gloss, dry film hardness, film adhesion, impact resistance, chemical resistance, resistance to corrosion caused by humidity and salt spray, as well as resistance to color fading or deterioration due to weathering. While the same basic testing is performed, the exposure conditions may vary among standards.

A pair of related FGIA standards, AAMA 611 and 612, describe test procedures and performance requirements for anodized finishes and anodized finishes combined with transparent organic coatings, respectively.

The series of tests for coatings on thermoset profiles, such as those made of fiberglass or molded aliphatic polyurethane elastomer, is AAMA 623, 624 and 625, another set of FGIA technical documents. They test for color uniformity, specular gloss, dry film hardness and film adhesion, humidity and impact-resistance, resistance to abrasion and cold cracking, chemical resistance and color fading or deterioration due to weathering in very nearly the same ways spelled out in the standards for thermoplastic profiles.

The “good, better, best” suite of standards for organic coatings on thermoplastic profiles (such as vinyl profiles) is AAMA 613, 614 and 615. All three standards set forth equal performance requirements for attributes such as color uniformity, dry and wet film adhesion, and exposure to excessive heat or cold. Other test conditions vary to determine “good, better, best” performance for the parameters of UV weathering and humidity exposure.

Rich Rinka is technical manager, fenestration standards and U.S. industry affairs for the Fenestration and Glazing Industry Alliance (FGIA).
rrinka@fgiaonline.org

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