This course is part of the Metal Architecture Academy

MCM STANDARDS

To ensure a high level of durability, color retention, abrasion resistance, and other characteristics, MCM panel finishes must be tested to ensure compliance with AAMA 2603, AAMA 2604, or AAMA 2605 standards. AAMA 2603 is a voluntary Fenestration & Glazing Industry Alliance (FGIA) Specification of the Performance Requirements and Test Procedures for Pigmented Coatings on Aluminum Extrusions and Panels. AAMA 2604 applies to High Performing Organic Coatings, and AAMA 2605 applies to Superior Performing Organic Coatings.

To meet AAMA 2603 standards, there are several good MCM coating products for interior applications where UV is not an issue including polyester, acrylic, and enamel. For AAMA 2604, 50% PVDF, the majority of SD polyesters and some FEVE coatings are capable to passing the tests required of the standard. For AAMA 2605, 70% PVDF, many FEVE, and a number of SD polyester coatings are suitable. That said, the pigmentation required for some of the brighter colors used in corporate branding applications, for example, are not as durable to UV light as the muted earth tones are. Consequently, there are some limitations with some of the bright hues.

According to FGIA, the specifications are intended to assist architects, owners, and contractors to specify and obtain factory-applied organic coatings, which provide and maintain a high level of performance in terms of film integrity, exterior weatherability, and general appearance over a period of many years. Consequently, metal coatings are tested with regards to chalking, blistering, cracking, fading and more. Not only do these standards help ensure that the market is providing high quality metal coating products, but the data gathered by this testing helps manufacturers continuously enhance and improve their formulas.

Delving into the details of AAMA 2605’s specific testing standards for factory-applied coatings, the following gives some background to the different aspects of appearance and performance, and how these qualities are measured;

• Color Uniformity: Testing to ensure that colors in production match specifiers’ expectations. Although instrumental color measurements are recommended in many applications, visual observations under controlled lighting conditions are useful in production environments for determining significant color mismatches and uniformity.
• Specular Gloss: This is the ability of a surface to reflect light at the same angle of incidence as the incoming source. High gloss surfaces scatter less light than low gloss surfaces. A gloss specification can be important because visual perception of color is significantly affected by the glossiness of the surface. Furthermore, change in gloss of a surface over time may be an early indicator of degradation of, or physical damage to the finish.
• Dry Film Hardness: ASTM D3363 describes a procedure for determining the dry film hardness of a coating by using a series of standard pencil leads of varying hardness to attempt to scratch or gouge the surface.
• Film Adhesion: ASTM D3359 lays out the test procedures for determining how well a coating film adheres to its substrate. This includes dry adhesion, boiling water adhesion wet adhesion testing.
• mpact Resistance: ASTM D5420 describes a method to compare relative ability of a material to resist deformation caused by physical impact on a small area. The test is useful in determining the ability of a coating or laminate to maintain adhesion to the substrate after impact.
• Abrasion Resistance: This test, specified as Method A in ASTM D968, determines the relative resistance to abrasion of a coating. A silica sand is allowed to fall from a specified height onto a coated substrate to abrade the coating until the bare substrate is exposed or a maximum amount of sand has fallen. The volume of sand (in liters) is divided by the coating thickness (in mils) to calculate the abrasion coefficient.
• Chemical Resistance: This test is designed to ensure coatings are resistant to cleaning products containing acids used to remove mineral deposits or construction mortars. Specimens are exposed to muriatic (hydrochloric) acid, rinsed and evaluated for blistering and visual appearance changes.
• Mortar Resistance: Because finishes may be exposed to mortar during building construction or maintenance, this method was developed to determine how well a finish resists permanent adhesion of mortar and changes in appearance upon removal of mortar. In the test, mortar is applied and allowed to condition at high humidity before it is removed from the surface by a damp cloth and a mild acid solution. Then the appearance is evaluated for visual appearance changes.
• Nitric Acid Resistance: This test is used to determine the ability of a finish to maintain adhesion to the substrate and to resist color and gloss change when subjected to nitric acid vapors. Nitric acid chemically reacts with polymers, and this test is designed to accelerate the effects of localized acidic pollution in the air, such as from vehicle exhaust or industrial processes.
• Detergent Resistance: As described in ASTM D2248, this test is used to determine the ability of a finish to maintain adhesion to the substrate and to resist color and gloss change when subjected to a standardized detergent. It is designed to accelerate the effects of repeated cleaning of a finish.
• Window Cleaner Resistance: This test is intended to determine the ability of a coating to resist damage from window cleaning chemicals. A standardized window cleaning solution is mixed, dripped onto a coated specimen and covered to prevent evaporation. After the exposure a tape adhesion test is performed, and the specimen is visually evaluated for blistering or other appearance changes.
• Humidity Resistance: The ability to resist moisture is a critical function of any finish. This test subjects specimens to condensing humidity for an extended period before they are visually evaluated for the formation of blisters which indicate loss of adhesion.
• Cyclic Corrosion Resistance: A modified version of the salt spray corrosion method, a standard test solution is applied to bare or coated metallic test specimens by combining the solution and compressed air at an atomizing spray nozzle. Unlike the salt spray method, cyclic corrosion alternates between periods of spray and specimen dry-off from air circulation within the chamber
• Weathering: Sunlight, temperature, and moisture in the outdoor environment degrade materials including coatings. South Florida is considered a global benchmark location for outdoor weathering tests due to its consistently high levels of sunlight, heat, and moisture. In the vast majority of cases, a material that performs well in this environment will perform well in major international markets.
• Chalking: Chalking is measured on an exposed, unwashed painted surface.


Photo courtesy of Daniel Lunghi Photography/3A Composites USA

The offset cladding design at the Olume residential building in San Francisco works with multiple colors of MCM panels.

WARRANTIES

While MCM finish warranties vary based upon the material’s physical properties, the type of finish and the specific application, the resistance to fade and chalk, and gloss and adhesion quality of many finishes can be expected to last 30 years or more. Warranties offered from the MCM manufacturers are pass-throughs from the paint manufacturers and are based on 30 + years of South Florida exposure testing.

WORKING WITH CERTIFIED MCM SYSTEM FABRICATORS

Another best practice for these metal exterior projects is working with Certified MCM System Fabricators. Meeting qualifications for years of experience, services offered, industry performance requirements and financial strength. Building teams are assured that the fabricator has what it takes to successfully fabricate and deliver high quality MCM cladding systems. A Certified MCM System Fabricator provides shop drawings and engineering calculations to verify the suitability of the panel system design before fabricating all structural components including extruded aluminum, fasteners, and clips.

“The need for experienced fabricators and installers is paramount to a successful installation. The precision and care needed to furnish accurate panels, then assemble often-complicated arrangements guides us and our construction management partners to seek out experienced subcontractors,” reports Drake. “Pre-certification by an impartial, industry-recognized program sets realistic expectations for workmanship that designers and our clients can trust.” With quality control procedures in place, a Certified MCM System Fabricator can identify problems early, avoiding delays and modifications. These fabricator systems also offer assurance that the fabricated system meets the specified performance requirements for water penetration, structural performance, and visual appearance.

In addition to meeting these performance criteria, “MCM design and installation require close coordination with other trades involved in the construction of the building envelope. A fabricator who understands and respects these critical issues is key to a successful project. Adding a Certified MCM System Fabricator contribution to that, we consider that an advantage,” says Rubenstein.

Hitting the Jackpot with MCM



Photo courtesy of Sobotec

A custom colored, three-coat PVDF coating lends a sharp look to the MCM panels cladding the Las Vegas Convention Center.

Thousands of people visit Las Vegas annually because of the flashy casinos, star studded entertainment, big name chef restaurants, and what goes on at the Las Vegas Convention Center. To match the Las Vegas total environmental experience. the LVCC’s ambitious plans for their 1.4 million-square-foot expansion included 157,000 square feet of Metal Composite Materials by a Certified MCM System Fabricator.

TSK Architects, in Henderson, Nevada, a leading architect and design firm with more than 60 years of experience bringing regionally sensitive modernism and sustainable design to Nevada. TSK’s complex modern design required the fabricator to tackle intricate geometrical challenges posed by the “Ribbon fascia.” The innovative approach utilized 3D Revit software, which not only met–but exceeded–expectations as an integral part of the project’s successful result.

Custom fabricated 3,000 individual custom MCM panels with a custom-color, three-coat PVDF white hue certainly brings the TSK Architects vision to reality. This custom color’s importance to the architect’s project team design went through nine custom submittals before arriving at the tenth and final color.