Corten - Colour, change and protection

1 May 2018

Creating the composition for change

Controlling the interaction between the natural world and the built environment is one of the most fundamental concerns for designers and architects. In most cases, this simply means ensuring the elements are kept out. Building façades, however, present an opportunity for much greater interplay and experimentation. Through the use of corten steel, architects can harness the weathering process, creating vibrant canvases which naturally change over time.

Corten Steel hook on cassette

Weathering Steel

Corten, or weathering steel, derives its unique character from a carefully balanced composition - incorporating low alloy elements, such as copper and nickel, during the smelting process. As with all steel, when exposed to the natural elements the surface of corten metal oxidises and forms a patina veneer giving the sheets a distinctive “rusted” look.

Henry Moore CORTEN WEATHERED STEEL AS A HOOK ON CASSETTE

​Rust as Protection?

The oxide layer is porous, causing it to retain moisture. In standard steel products, this will inevitably lead to further corrosion over time. The alloys within corten steel, however, help to form secondary layers which are resistant to water ingress and help to limit further corrosion of the metal. As a result, it can be used in outdoor applications without the need for a protective paint layer.

We specified Kingspan’s BENCHMARK Weathered Steel / Corten Hook-on cassettes for the new archive for the Henry Moore Archive Foundation because it is a beautifully engineered system offering a timeless visual elegance that compliments very well our design intent for the project. The Weathered Steel / Corten cladding looks stunning against the backdrop of the beautiful gardens created by Henry and Irina Moore.

Hugh Broughton Architects.
Henry Moore CORTEN WEATHERED STEEL AS A HOOK ON CASSETTE

Autumn Colour

Much like autumn leaves, when the patina first forms it takes on a yellow shade. If the corten is left uncoated, this colour will gradually shift to a vibrant orange before settling to a dark red after several years of exposure. The speed of the colour transition is dependent on the frequency of wet and dry cycles the steel undergoes.

Henry Moore CORTENCORTEN WEATHERED STEEL AS A HOOK ON CASSETTEWEATHERED STEEL AS A HOOK ON CASSETTE

History of Corten

The American Society for Testing and Materials first began conducting tests to clarify the benefits of incorporating a low percentage of copper and phosphorous into steel in 1916. Building on this research, United State Steel began testing its own steel and alloy composites in 1929 and in 1933 it patented Cor-Ten A (subsequently joined by Cor-Ten B) The products took their name from an abbreviation of two of their main properties - Corrosion resistance and Tensile strength. These benefits, in addition to their relatively cheap pricing, saw the materials used in a variety of industrial applications such as rail carts in collieries.

Corten in architecture

Eero Saarinen is often credited as the first designer to make use of weathered steel within an architectural context. In shaping the headquarters for John Deere, an Illinois based farming equipment manufacturer, Saarinen wanted to create a building which reflected the rugged, honest nature of the men who’d formed the company. His solution was a modernist design, blending glass with a corten steel frame which would develop a “deep hue, similar to that of the oak trees” which surrounded it.

Since then, corten steel has been used in an increasingly wide variety of applications, from shipping containers and bridges, to garden furniture and iconic sculptural pieces such as the Antony Gormley’s Angel of the North. The material can be incorporated within a structure in a number of ways, but one of the simplest and most popular remains its use as a rainscreen façade.

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Corten Steel hook on cassette Corten Steel hook on cassette
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Changeable Creations

Queens Uni in CORTEN WEATHERED STEEL AS A HOOK ON CASSETTE

As with any distinctive façade material, corten specifications require considerable thought and planning, however, as a growing number of projects have shown, when used well it can deliver truly iconic buildings which will continue to change and surprise over time.

One project that showcases the multi-faceted aesthetic suggestiveness of the material is the David Kier student hub and auditorium at Queen’s University in Belfast. Completed in 2015, the corten-clad modern pavilion both contrasts with the neo-Georgian David Kier building, whilst simultaneously reflecting the varied orange colour of its brickwork and the city’s ship-building past.

The colour of passion, life, strength victory and danger – red is certainly a colour which carries a wealth of symbolic meaning. Our next blog in this series on colour in architecture will try to deconstruct the effect of this evocative shade.

Available Cassette options in Corten Steel

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