Anodized Aluminum Surfaces Give 100 Kings Highway a Stunning 3-D Visual Effect and Sustainable Future

For the landmark residential tower recently completed near the Gateway Arch in St. Louis, the texture and finish of the prominent metallic surfaces needed to be just right.

These aluminum surfaces really stand out, at about a 10-degree angle, in tiers of 4-story-high leaves that suggest a golden crown. Architecture writers heralded the confident symbolism of this first St. Louis project of the hot and prolific Chicago architectural firm Studio Gang as “the giant crystalline headdress” appropriately located at 100 Kings Highway.

Reflecting its surroundings

The name, “100 Above the Park,” describes the design concept: by tilting the curtain wall system towards the greenery of Forest Park below, the apartment complex was specifically designed to connect people in the interior to the surrounding environment.

From the outside, the downward angle of the glass-and-metal facade of the 380-foot-tall tower reflects the changing light and seasonal beauty of the landscape, and marketing literature promotes the design as a dynamic backdrop for the sprawling park’s fall foliage and snow-covered trees.

Vibrant metallic look

The design also called for a metallic finish comparable to the way that the stainless steel surface of the Arch takes on the color of the sky as weather changes and as the sun moves across the sky from dawn to dusk.

To achieve the desired look, the architect researched the exterior materials very early in the conceptual design process of the 37-story, 540,000 square foot building. The tilted rainscreen panels would be composed of lightweight aluminum and attached to non-bearing cold-formed steel framing.

The owner and architect choose a corrugated pattern for the texture of the aluminum panels. The next step was to find a surface finish that could achieve a highly reflective, but diffuse look.

Side-by-side comparison

After researching the options, they chose two different finishes. A pair of aluminum panels were fabricated with the same corrugated texture. One panel had a painted finish applied. The other panel was fabricated from anodized aluminum from Lorin Industries, with ClearMatt® finish, Architectural Class 1.

The two samples were evaluated in bright sunlight on the roof of the architect’s offices in Chicago. Next to each other, the anodized aluminum appeared vibrant, and the painted surface looked dull. The anodized aluminum finish was selected for the corrugated rainscreen panels and flat trim panels on the façade as well as for fabricated ‘blades’ over the garage area.

Three-dimensional visual effect

Anodizing aluminum builds a crystalline structure that reflects and refracts light in a way that creates a three-dimensional metallic look you just can’t get from paint—precisely the look sought by the architect.

Unlike painted metal, anodized aluminum is not flat, static, or one dimensional. Depending on the angle from which it is viewed, it can achieve ever changing looks due to variables such as the amount of light, time of day, or even the time of year.

Long lasting and low maintenance

The architect and owner wanted to achieve a striking visual appearance that would age well and retain its exceptional aesthetic qualities for decades to come with minimal maintenance.

The key difference is that—unlike paint—anodized aluminum is not a coating.

Anodized aluminum is created through an electrochemical process in which a very hard oxide layer is grown from the aluminum itself, rather than being painted on or applied. The raw aluminum is bonded at the molecular level to create a surface that is thick, translucent, and very hard—much harder than the base aluminum itself.

In fact, the surface hardness is second only to diamond and is therefore unmatched in abrasion resistance and durability. Therefore, anodized aluminum is much more durable than coated materials and will never chip, flake, or peel and will never rust, patina, or weather.

Moreover, Lorin Industries delivers an exceptionally high quality and long-lasting anodized finish using a special process where coiled raw aluminum is unwound and pulled through a series of tanks that clean, anodize, color, seal, and finally rewound into the coil—all in one continuous movement. Because every square inch of the material in coil form spends the same amount of time in each part of the process, consistency of color and texture is ensured.

Most sustainable option

Lastly, the anodized aluminum was chosen not only for its distinctive and long-lasting appearance but also for environmental sustainability.

Anodized aluminum reduces solar energy absorption. It typically has a higher SRI (solar reflectance index), meaning more of the sun’s heat energy is reflected away from the building, compared to coated or painted surfaces and thereby keeps buildings cooler, mitigates the urban heat island effect and reduces energy consumption costs.

After oxygen and silicon, aluminum is the third most plentiful element on earth and anodized aluminum is also a 100% recyclable product with higher dollar value than scrap painted aluminum.

In a city that takes pride in the architecture and historic symbolism of the iconic Gateway Arch, 100 Above the Park stands as a vibrant, optimistic symbolism of the future.