This course is part of the Metal Architecture Academy

FINISH TYPES

To get into some more details on the many different finish types available, architects have quite a number of options to fit their application. The more basic solid painted finish is available in a plethora of colors and is ideal for a wide range of projects, including corporate branding applications.

Effect finishes include micas and metallics, which are typically created with all the high performing resins. Sample mica colors are silver, platinum, champagne, and gray. Micas lend a pearlescent type of an appearance. Since the mica and metallic flakes tend to lie at different angles, they catch the eye by dynamically reflecting the light bouncing off the MCM panels based upon the intensity of light and viewer’s angle.

Examples of metallic finishes include silver, gold, steel, bronze, and copper. These finishes, combined with the composite panels, enable designers to achieve the look of natural metals without the expense, maintenance, and instability of natural metals. For example, copper and zinc naturally oxidize and patina over time. A wide range of color and gloss options deliver the clarity and luster of pure metal.

To achieve the desired look, these types of finishes require a primer, metallic base coat and clear topcoat, thus necessitating a three-coat system. To ensure color consistency for both mica and metallic finishes, it is recommended that project teams order the finish at one time from one material batch. It’s also important to note that both micas and metallics are directional. This means that the manufacturer needs to provide the proper directional arrows and the fabricator must check that the arrows are properly aligned to achieve a uniform look. This applies to on-site panel erection as well.

Another product category is color shifting or prismatic finishes, which are also directional and therefore follow the same parameters as micas and metallics in terms of fabrication and construction. The effect of a color shifting application is that the colors appear to change when viewed from different angles or based on the weather and time of day. “Color shifting and special effects allows the building to be alive and adapt to the surrounding conditions. It changes from dusk to dawn and from season to season,” observes Le. Like metallics, color shifting finishes require a third prismatic topcoat, which incorporates specialized mica flake pigments. This is applied on top of the primer and color base coat.

With advanced faux stone and faux wood finishes, buildings can benefit from the authentic look of these natural materials without the additional cost, weight, structural implications, and maintenance. A natural stone finish can be created through the application of a transfer process over a color base coat, which introduces the grain patterns of polished or flamed granite. A topcoat then seals in the natural stone look. A similar process is applied to wood grain finishes. A wide variety of wood species can be replicated including mahogany walnut, maple, teak, and bamboo just to name a few available. Some additional specialty finishes include terracotta and textured with multiple colors.

Commenting on the variety of available finish types, Drake says, “We are fascinated by the finish range of MCM panels. We seek mirror finishes on more sculptural designs, color-shifting finishes for public facing facilities looking to make an unforgettable impression and wood appearances to establish a humane, relatable experience that demands low maintenance.” In a similar vein, Rubenstein says, “We've seen a range of, and interest in, new visual effects in recent years, such as custom color-shifting panels, wood- and stone-look panels, and patinaed panels.” At the same time, he points out that some of these selections can fall outside of a project’s budget. That said, there are times when the project team can work closely with the manufacturer to achieve an economy of scale if the design is able to minimize material waste during fabrication, and or save time/difficulties during installation.

Another feature MCMs offer is their ability to incorporate multiple finishes on one project. “The simplicity of detailing one system across multiple finishes delivers a more reliable weatherproof building envelope while also reducing the number of trades needed to enclose our buildings,” notes Drake. “Simpler detailing and reduced construction labor translate to greater reliability and lower cost.”

Photo courtesy of Daniel Lunghi Photography/3A Composites USA

This hotel porte cochère in Los Angeles features MCM panels finished in a white gold color shifting finish designed to amaze.

Photo courtesy of East Coast Metal Systems

The wood grain coating on MCM panels provides the warm look of wood with the durability and low-maintenance of metal.

COIL COATING PROCESS

An important aspect of ensuring highly durable, top-quality finishes for MCM sheets is the application of paint prior to the sheet manufacturing process. While paint can be spray-coated in the factory, the industry-accepted standard for MCM is coil coating. “Factory finish application assures a level of consistency that is typically expected of precisely detailed products like MCM. The peace of mind of reduced manufacturing steps further guides our preference for coil coating over other finishing methods,” Drake explains.

Coil coating is the method by which a metal coil is coated in a continuous process prior to the actual assembly of the MCM sheet. The result is a uniform, high-quality coated film thickness surface. Continuous coil coating manufacturing utilizes either roll coating, reverse roll coating, or a die coating method. Reverse roll coating applies paint with two rolls running in opposite directions. A metering roll is used to load and transfer the paint to an applicator roll, which then applies the coating to the substrate. This process provides good control over the paint thickness.

Die coating is a precision coil coating process also offering the advantages of high-volume, continuous process coating, but with even greater paint control. The paint is applied directly to the substrate through a slot die extrusion system.

In both cases, continuous manufacturing allows lower costs and greener manufacturing with reduced waste and increased efficiency. In addition, coil coating offers greater flexibility in the type of pre-treatment, paint chemistry, and texture that can be applied. Furthermore, coil-coated metal products are more durable with life expectancies of up to 40 years before repainting is considered. They contain lower waste emissions, including water and VOCs, and they lend a higher level of safety with their automated, industrialized application process.

The coil coating process is done prior to forming so that the entire surface can be cleaned, treated, and coated in a flat state, which improves the coil width and consistency throughout the run. Coil coating is also the only paint system capable of meeting the most referenced architectural performance specifications delineated in the American Architectural Manufacturers Association’s AAMA 2605 standard.

Photo courtesy of Precoat Metals

By coil coating the panels in a continuous process prior to the actual assembly of the MCM sheet, the finish adheres as a thick, uniform, high-quality finish.